Personally I would start out small outlay wise, buying items that will do the job but probably not give you years or worth compared to the top end market gear, then upgrade as you go to bigger and better gear as you get more and more work in.
Main things in my view that you need are 2 wet cutters and 2 dry cutters, a large and small one of each for different jobs.
Many swear by Rubi, and by all accounts it's a very good make of cutter, but there are other cutters that do just as well at nearly half the price.
I am still using a cheapo Plasplug dry cutter for
standard small to medium sized ceramics and have the Husqvarna TC670 for large format tiles upto 600's, and likewise a small Plasplug wetcutter and a Master Tiler for larger tiles.
It all comes down to if you really have money to burn when setting yourself up or not, but the way I look at it is if you start off small and buy sparingley and only upgrade through proffit from tiling then your obviously getting more than enough work in to be able to upgrade tools, hence it will make sense to have better gear, but if your struggling to get enough work in to be able to afford better gear, then you don't really need better gear if you have not got the work coming in.