the cheapest way is to spraypaint it yourself, get some good quality paint, from HQ in brixton or 4d model shop near tower bridge, it will cost about £3.50 a can, then take off everything you can from the bike and mask off everything else, make sure the bike is clean, you probably want a layer or two of primer, which you can get from a hardware shop. and then paint the bike, dont spray a lot on in one go, do a number of thin layers leaving it do dry inbetween, then put a clear layer over the top if you want.
the cheapest way is to spraypaint it yourself, get some good quality paint, from HQ in brixton or 4d model shop near tower bridge, it will cost about £3.50 a can, then take off everything you can from the bike and mask off everything else, make sure the bike is clean, you probably want a layer or two of primer, which you can get from a hardware shop. and then paint the bike, dont spray a lot on in one go, do a number of thin layers leaving it do dry inbetween, then put a clear layer over the top if you want.
http://www.instructables.com/id/Bike-Painting-Tips/