I'd ideally like a 33t, but I suppose I'd settle for a 34t if I was pushed.

Forge MTB used to do them, but they've stopped trading.
BETD only do suspension thingies.
I've googled for it and can't find anything useful, so does anyone here know where I can buy a 33t or 34t SS 4 bolt chainring online?

Some BMXy people might if you are running 3 piece cranks.

you could try the DMR saturn and similar as they are suitable for SS. You will prob have to go 32 or 36 tooth though

I got a 34t Blackspire from CRC. It's a DH single ring so doesn't have the ramps.

32t (plus many other sizes) are available and in silver or black