Rob , it need not cost a great amount to set up a small facility but there are two essential items.
You will need some way of de-waxing and firing the moulds , typically an electric oven of suitable size and able to reach 750°C , you could probably use a domestic cooking oven with extra insulation , or use the elements in a Kaowool lined metal box.
The oven will need a programable controller , again if you are so inclined you could use a PC , my first oven used an Apple IIe with home made I/O board , but for around 100 USD you can buy a good controller.
Secondly you will need a source of high vacuum i.e. at least 28" Hg in 2 minutes. I have an Edwards laboratory high vacuum pump which new would be over a 1000 bucks but if you look hard enough you can get a used one for peanuts.
You will need the pump for de-gassing the investment cement and assisting the mould filling.
Some stainless steel tube large enough to take your castings with at least 1/4" to spare , but mild steel will work, just doesn't last as long.
I spent almost nothing on my first lost wax foundry , now it is a business I tend to buy what I need unless I can make it better.
the rest is consumables ,my process uses commercially produced plaster based cements , but you can make your own , not so reliable but it works.