What's the most cheapest way to get rid of a body?

legal or otherwise?

Usually the most cost effective options are a home funeral, natural/green funeral, or cremation/aquamation (could be wrong on the name here) without embalming. You can also donate your body to science and if accepted they will cremate your remains afterwards and return it to whoever you predesignate.

Donate to science. 

There is no legal requirement to have a funeral.  Call his doctor (or yours if you don't know his) to pronounce him dead and then call a funeral home and ask them to pick him up.

Find an ethical funeral home that won't rip you off for a cremation. 

Its called cremation. But where is he? What if you leave him?  You are not obligated to go get him I don't think? Makes me think i should go ahead & pay for mine so my heirs don't waste money on a funeral scam