My suggestion is Obviously a nice set of comfy thermal lens mask, then get a hopper, hoppers range from £30-£200 and they can go on almost any gun. so you turn up at a rental site and use one of there guns with your own hopper you instantly get a better gun because the hopper will feed balls as fast as you fire them and wont chop paint! once that is sorted you then look at getting a gun, this all depends on what you want to do. My suggestion is either get a nice woods ball gun (e.g. i have an A5 and had no problems with it at all! plus is comes with a cyclone feed system so no need to get a hopper before hand) or you get can get a low-mid range tourney gun. i would suggest Empire invert mini or an AXE.
Bear in mind tourney markers are not meant to be used with C02, so if your local site has C02 you cant use it there unless you purchase your own air bottle.