the pre wedding photos are a must in Hong Kong for Hongkongers. but the companies really do take the pi$$ out of it, it's a real money making machine. The packages are expensive and you get a fixed number of photos, but if you want anymore photos (and believe me you will once you see them) then they are individually priced. I went to 2 of them, and both were just as biting as the other one.
I did hear though that Macau and Taiwan pre wedding photos are cheaper, but of a lesser quality and mostly it's all "green" landscape if you know what i mean. Their interior photos aren't really good.... but they are relatively cheaper than hong kong. However... you need to weigh up the flight costs, time off etc to get there. For us personally, we didn't just didn't have the time nor we wanted the hassle. But a lot of hong kong couples do go over there for their pre wedding pics.
You should head down Kimberley Road in TST for the pre wedding pics if you decide to stay in hong kong, the whole 2 streets are lined with them.
goodluck!!!