Estimating price of a house

[bdasites]

Hi,

I am looking at buying a house, but finding it difficult to estimate the correct price. Here is what I am following as of now:
Step 1. Estimate land price. Find the plot size and exact location of the house. Find quoted prices for plots in the that area on sites like 99acres.com and magicbricks.com. Reduce average of quoted price by about 10% (negotiated price will be less by at least 10% I believe). Is 10% a fair figure?

Step 2. Estimate construction cost. Find exact built-up area. Examine the house to get an idea of the construction quality. Multiply built-up area by construction cost per sft (Average: 1000/sft, Good: 1100/sft, Very Good: 1200/sft, Perfect: 1300/sft). Does this make sense, and are the numbers fair? Also, what does built-up area include? Does it include parking, utility area behind kitchen, any gap from boundary wall to house, balconies?

Step 3. Estimate for amenities. Wood-work (for Kitchen, bed rooms), Chimney, ACs, any extras you get with the house. For wood-work in a 3BHK house, I am estimating at 2L for Basic (plywood+hard wood), 3.5L for Good (better finish than Basic, better wood), 5L for Excellent (pre-built cabinets from Retail stores). Is this fair?

Thanks in advance