Grind your rear rim and get some decent v-pads, CNC heatsink pads? About £20. Trialtech bars , get them second hand off here if you can find one. They go for about £30 ish, then get some trialtech foam grips, £6. Stems, look for something in For Sale section such as echo team or trialtech sport stems, you might be able to them about £20ish. They have less rise than your current stem but nice riser bars with headset spacers will raise the bars up a little. If you can splash out a bit more, you could change the forks but the only advantage is save a bit of weight and maybe strength depending on which ones you buy. Curved forks will also increase your wheelbase by a few mm, 5-10mm maybe. If you don't mind the forks, spend some on other little things like cheap but grippy pedals or a chainstay protector? EDIT: FFW is less hassle than a freehub, if they go wrong and you need to replace it you have to debuild you wheel which is annoying. FFW you just take cranks off and unscrew it. The deng range of freehubs are known to skip, search the forum you'll find a few topics on them.