Pretty sure that's not just some realistic dog drawing. There are sizes and all given, the things that you have to use, and you probably have to ship them the drawing. I think that costs much more than 5BTC when you go to a gallery or if you do bidding. It all depends on your work, though.
Anyway, if you want a job that pays in BTC, you also have to work something that's BTC related. I actually just participate in signature campaign and some altcoin bounties but that's not necessarily a "job". Usually online, the jobs that you can do aren't stable. For example, if you can do photoshop, it's not everyday when somebody's looking for a photo editor. And keep in mind that the competition is quite good.
Tasks and jobs from a certain website do not pay that much. My advice, just post in the services section and then post the same thing in some other forum but just say that you're the same guy so they wouldn't think that you just copy+pasted it.