celica question + how much should i pay?

I'm in the market for a cheap 94-99 generation celica. My budget is $2500, so i'm looking to find a good deal. First off, if the owner claims the celica has been properly maintained and has records,etc.. how many miles can i squeeze out of it? how many miles min. you think?

also, my friend knows someone who is selling a 94 celica st coupe 150k miles, all records,etc good condition for $2900 on craigslist.. is this a decent price? what should i try to lower it to?

how big of a difference is a st and a gt? in terms of power and cost?

2900 is a little high for an st with 150k, its not too bad though as that car will easily last 200k.

gt-135hp
st-115hp

so how much should i offer to pay? what price would make it a "good deal".

if its in good condition i wouldnt offer over 2500. i paid 1800 for my 90 gt-s with 153k.