Who'd be dumb enough to part with a Rallye for £1500?
I remember my first policy on a Mk2 1.8 GL was about £1200, but that was my very first car when I was 20 with zero no-claims.
£1500 could get you a decent enough Mk2 16v, 138bhp, but just get an unmodded car, then you can mod it later when your insurance has come down. Do what Dizzie has done, start with a standard Mk2, then stick a 1.8 Turbo lump in it later, get yourself 200+ horses.
If you like the square lights from the Rallye, you could always fit a Rallye grill and lights (but they might be hard to find), the cheaper alternative is a Jetta grill and lights.
But you won't find any sort of body kit to give you the flared arches and body of the Rallye.
Whatever you do, don't buy a Mk3 GTI for that price, cos it'll be a lemon.
Read some of the buyers guides around the place, take your time, don't buy the first thing that comes along.