Ebay, but i'd check the price of new because 2nd hand prices can be daft. Having said that you're 1st projects should be making you're own, they aren't hard to make and they're good practice, you just need some mild square bar
It depends where your interests lie - if you’re keen to learn anything then make your own tools - a good pair of leather gloves and longish bits of steel you can start making them with no tools. If you’re in a rush to get started there’s no shame in buying tools - I have a mix of bought new, used and made stuff, though most of my old tools are a bit iffy in terms of quality and usability.
Vaughans in Lye,sell new smithy equipment,I bought my power hammer from them in 2002,they had stores full of it & as said second hand stuff ,is sometimes out of reach of the folk that actually want to use it,as it’s become trendy,the only realistic prices I’ve seen in the last 10 years,has been vintage rallies,good luck.