I have 2 Peter Childs pyrography machines and use 24 swg nichrome wire. I do mainly lettering for signs, keyrings and various turned items. I have a heavy duty machine for doing big house signs etc. It is a good idea to wear a mask or have an extractor because it can be quite smokey. There are people who do amazing pictures on various social media groups. In the old days they used to call burning onto wood poker art.
If you want to do have a wide nib for a thick line for signs you can coil the wire around a nail and squeeze it with some pliers. You can buy various nibs. You can get a machine now that you can plug 2 pens into so yoy can alternate between different pen wire thicknesses. I would guess £100 would set you up with machine, wire, nibs etc and would soon get your money back on your first few jobs. For wood blanks you could try a joinery shop or a sawmill often has a corner with odds and ends.
In addition to the burner you might want to get a fret saw, electric planer, band saw, pillar drill and a small lathe. There is lots of old uaed machinary out there that is in perfect working order.