smoothing of the rubstrips, another 50-75 quid tops (epoxy and fibreglass isn't that expensive nor time consuming)
Bumper basic spray job - 100-125 quid
smoothing and spraying of the front grill piece around 60-70 quid (i've paid 30 and 65 from different bodyshops).
wouldn't bother touching up the splitter, it's a stock non GTI splitter, cost 20 on ebay.