Hi Alex and welcome. When you say you have a budget of 2500, do you wnat to buy a ready made cafe racer or a basic bike and mod it yourself?
If you're looking at ready made take a look on E-bay, just type in cafe racer and search and you'll come up with a fair few in that price range. If you've just passed your test then look for a smaller bike, say 350-500cc and get used to it before going loopy. Too many young riders get hurt by jumping straight off the riding school hack onto a 140bhp monster before getting used to the power!
Just bear in mind, one man's perfection is another's bodge job and you need to be very wary of a modified bike. We build cafe racers to ride and the mere racing stance means that some will have had a tough life. Look for oil leaks, smoke on start up, listen to the engine and if you're not experience take a mate who knows bikes. The engine is the big expense, most of the rest is cosmetic.
So, don't let your heart rule your head, if it looks too good to be true it probably is, and if in doubt double your money by folding it in half and putting it back in your pocket, and walk away!