I have bought a little diesel heater to try out.
My workshop is well insulated but this time of the year its getting really cold inside. This heater runs quite cheaply on diesel it looks like round 1/2 litre per day and keeps the workshop a lot warmer.
total cost was circa £130 plus £6 on diesel which looks like it will last a week or so.
All in all I think its a pretty good way to heat a small workshop however its quite noisy, clearly not a problem for most people but a bit of a pain in the behind if you make you tube videos.
Cheers