Winter outside heater recommendations?

[spectrrr]

Winter is arriving and I've go a great little makeshift mancave setup outside in a little uninsulated shed. Well, it would be great, if it had a heater!

I haven't measured the shed, but it's probably not more than 11x9x8, and really only 1/2 of the shed needs to be warm.

Quick startup is needed - I'm not going to turn it on and come back in 45 minutes. (so a fan is probably in order... but maybe not?)

Electric would be preferred, less things to worry about. Given that I'm smoking right next to the main breaker box for the property, getting a good power feed to it won't be a problem (electric may be too $$ to buy however)

Heater can (and will) be positioned somewhat close to me. I can't physically put it more than 4 feet from me.

$PRICE$ is a factor. I'm not worried about operational costs, as it won't be used ever day. But for the initial unit, price needs to be low! ideally less than $100.