Ok this is easy
Time v Money v Ability
I would say this; if you have the money buy a chassis ready made and wishbones,the time ,effort and frustration it will save is immense but if you have the ability then making your own is very satisfying( where did u get that mister? " i made it ") very good feeling.
Also if you get bored easy then i would buy a chassis ready to assemble.The worst part i found is getting the wishbone brackets in the correct place and need to be accurate which is a real shit to do.If you are keen to do some welding then a pre cut chassis would be good,i think HandyAndy still does them on here?maybe message him.
You can get a deal from most suppliers if you buy more you geta better deal.(a chassis is around 600 quid)(bargain i reckon)
NTS(saturn) dunno website but should be easy to search/find also
Talon who has a site and also on Ebay.