depends on where you are gonna race, your ability etc etc
easy part first is esc. you cant go wrong with a hobbywing 120A. these are cheap and where some of the top brands get their own bits made with a different sticker
these can come as a combo although not sure if the hw motors are on the homologation list. if not then any from speed passion, hpi etc etc are all good quality and can be found around the £55 mark (especially if brought with a speed controller as part of a deal).
lipos on the brca list all have to conform to a maximum size and will all fit the b44.1 and can be found on a budget as well. intelec are on the list and can be found for aprox 50-60 depending where you shop, vampire, smc, hpi, can all be found at good prices as well.
check the brca lists then contact any of the shops on oople, racer or radio race car or your lhs for prices
Nathan