However, there are ways to cut one's renovation budget to keep blowouts at bay.

One, says Lehar - which he recommends as the "safest route" - is to engage a reputable designer. Many renovators already have a good idea of what they want, and think they can save money by going straight to the contractor. But if they are expatriates who do not speak Cantonese, communication problems inevitably occur.

Lehar says renovators can trim their designer's time by doing concept drawings themselves. But he says there are myriad other ways to cut costs.

Practical tips include laying new tiles over old - a process he says is reliable now, thanks to modern adhesives. "This saves time demolishing the old tiles and removing cabinetry, and will add only 4 to 5mm to the floor height," Lehar says.

Old-fashioned wooden floors can be given a lift by nailing lighter, contemporary floorboards directly over the existing flooring. Even cheaper is to lay laminate flooring.

"Engineered wood costs around HK$70 per square foot, compared with laminate at HK$16 to HK$20," says Lehar. A laminate floor can also be installed in less than half the time of regular wooden floors.

"Some of the old Chinese wood is really good quality but just out of fashion [too shiny or the wrong colour], but this can be easily polished off," he said. "Removing the top 1 to 2mm and revarnishing it to look brand new with a more modern matt finish is cheaper and better for the environment."

Recycled chipboard is another option.

Invest in good paint, he advises, because it is your best defence against mould and other humidity-related problems. Spray-painting can give an instant facelift to doors, avoiding the expense of replacing them. Windows, if in good condition, can similarly be repainted in a lighter colour.

Trawl Wan Chai or Mong Kok for hardware and sanitaryware savings, Lehar suggests. "A tap can cost HK$2,000 or HK$10,000," he says.

Much can be saved through construction techniques, says Lehar. For instance, using plasterboard for internal walls is cheaper than masonry.

With electricians charging on a per-socket basis, choosing floor and table lamps rather than fixed lighting, and power boards in places where they cannot be seen, will cut labour costs. And dimmer switches added to existing light fittings will help create a softer mood, inexpensively.

In the kitchen, tired-looking Corian counters may be given a new lease of life with a polish. Likewise, new handles and quality drawer sliders can make existing cabinetry far more pleasant to live with.

Finally, says Lehar, keep a close eye on the renovation works - as discrepancies will compound costs the longer they remain undiscovered.

Lehar estimates the cost of a typical renovation, by a professional company, to start from HK$850 per square foot, including a new kitchen, bathrooms, windows, gutting out and rewiring, using mid-range fittings.

Juliana Rotmeyer, principal designer at JAR Design, has seen her share of "sky's the limit" renovations. "The [renovation] process has so many variables. I've heard multiple stories of costs doubling and tripling after the initial budget has been signed," she says.

One reason this happens is that the designer forgets to include in the initial budget work that needs to be done, Rotmeyer finds. So a clear understanding of the renovator's goals and the scale of the works is imperative from the outset.

"Check and double-check the budget to make sure that all work needed is listed," she says. "Don't hesitate to ask your designer as many questions as necessary to clarify this list before signing."

Second, know what you want: changing your tastes and choices late in the game can be costly. "Contractors in Hong Kong don't tend to deal well with change, even if they are being paid for their time," she says. "Keep them and the budget on your side by knowing what you want before signing for it."

But cheap is not always cheerful. Countless renovations in Hong Kong are done with the tightest budgets in mind and the result looks generic, Rotmeyer says. "A good designer can potentially give investors an additional HK$2,000 to HK$20,000 per month in rent." Not to mention better resale value, she adds.

Rotmeyer, too, makes Wan Chai's hardware strip her friend. "One stroll down Lockhart Road and you'll quickly see the range in pricing on products like taps and bathtubs.

"Ceramic bathtubs are less than half the price of iron ones. Or you can scrap the tub and just go with a rain shower."

In the kitchen, Rotmeyer recommends cutting costs on cabinets, but not on the countertop. Stainless steel makes an effective work surface: it is durable and antibacterial, has good longevity and is affordable.

Finished concrete flooring is probably the easiest and trendiest way to save some cash on your renovation, she says. Add colour to the concrete for warmer finish, and a top sealer for shine if that is the preferred look. Layer antique rugs on top, or have carpets made to your own design.

Finding ways for fixtures to do double duty can also save in the long run.

If you are really strapped for cash, there is always what Rotmeyer calls an "aesthetic transformation". "This can be done when renting or owning," she says.

"With a design eye, it's possible to rework what a client already has. Adding accent-painted walls, changing the lighting, rearranging furnishings, adding soft furnishings like throws and pillows, and, finally, art can completely transform any space."