I thought about one of those too. My buddy who is a mechanic has one of those. But he's had a lot of problems with oil that had water in it, etc. And even though the previous owner left me every single drop of oil he ever drained out of anything for 20 years it seems, I don't think I could produce enough otherwise to fuel it.
I just called Tractor Supply. They have this one for $999. The reviews are mixed.
United States Stove Pellet Heater with 140 lb. Hopper, Large - 1098925 | Tractor Supply Company
You would have to get more than a few people to regularly supply you with oil.
Your friends problem could be that he's not careful with the oil. If you allow containers to sit outside in the rain, you'll going to get water in them. You also have to periodically drain the bottom "off" to get any water out.
I bought mine from a guy on craigslist for $500 and spent about $500 rebuilding it. It burns about 1 gallon per hour.
I am very careful with how I fill it. It's amazing how well it works. there's no smoke at all. from the outside, you cannot even tell it's running.
If you have any (free) access to regular and scrap wood, you might consider a regular wood stove. Pellet stoves work well but you do have to buy the pellets and clean it out periodically.
You also might look into a regular (new or even used) gas furnace and re-jet it to operate on propane. You can find 100gal propane bottles fairly cheap and there's usually no permit required for them because they're considered "portable"
I bought a new 60,000btu Janitrol (Goodman) 90%efficient furnace several years ago for about $600.
It vents through plastic pipe (the exhaust is that cool!!)
If I was going to heat a small shop, I use something like below.
The below furnace would probably run all winter on 100 gallons in a shop depending on how well insulated it is and how big......since you're not out there all day and night every day, you could be fairly frugal with the propane. Also, most people like it around 60-65 degrees when working in the "shop"
TAPPAN 1 STG MULTIPOSITION 40K 92.5 % GAS FURNACE | eBay
This one is similar to the one I installed in my previous house. It vents through 2" PVC pipe and most of them are "close combustion" meaning that they use outside air for combustion air and take NO air from the area where they're installed. (meaning you can have explosive atmosphere in the area and it WON'T ignite because the combustion chamber is completely sealed)
69,000 BTU Goodman Gas Furnace 92.1% GKS90703BX | eBay
The above furnaces are pretty easy to install. You wouldn't have to have a lot of ducting and the propane connections and parts are easy to hook up if you don't want to pay someone to do it. (the propane conversion is basically changing the jets and changing the supply pressure.....you measure the pressure with a water manometer)
AND you don't have to light them or clean them!!! They use hot-surface ignitors. (NO pilot lights!)
depending on how much you'd run them I'll bet the cost of the propane wouldn't be a much more than pellets and you wouldn't have to take up a pallets sized space in the shop to store the pellets. Also, you'd only have to call the propane service to have them fill it once in a while.
Cheers,
Rick