improting is a risky and long drawn out process.
try reading <a href="http://www.p8ntballer-forums.com/vb/showthread.php?s=&threadid=9760">this</a> before your too tempted.
i would also say save at least £100 and try again most likely in the second hand market.
If you havent got any goggles yet i would recomend getting those first, and get a decent set when you do.
JT Flex-7, Vforce (a wide range) you can get them from £30 up, and worth investing in as they are the only part of compulsary safety equipment.
if you want a cheap marker with the scope to upgrade try looking at a spyder, inferno, or (im waiting for neddyboy to pounce) a tippmann. each have their up and down sides. but they are all competative at an entry level. (just dont expect to play tourney ball with them)
and tippmanns can go REALLY cheap.
but i think its the 3rd time ive said this to someone today, TRY B4 U BUY, try as many as you can before you invest your hard earned cash in a marker.