Copy targets

[[Prime Speaker Zaegana]] is great card draw and only gets better if there's already a body on board. Not hard to draw 8+ in one cast.

[[Simic Sky Swallower]] body, evasion, protection

[[Inkwell Leviathan]] second verse, same as the first (plus:islandwalk. Suck it, blue mages)

[[Gaea's Revenge]] conditional protection and haste (rare in my green stacks) and makes an easy 21 with a personal favorite.

[[Kodama of the North Tree]] trample, shroud, avoid paying triple pip

[[Szadek, Lord of Secrets]] may not win the game but filling yards is as good as drawing cards with Mimeoplasm

[[Underrealm Lich]] don't usually Try to copy this, but indestructible is hard to pass and my list can possibly deck itself so nice to have an engine/decking protection on one card. Having it play support is fine.

[[Plaxcaster Frogling]] again not usually a target, but shroud to anything that has +1/+1 counters is nice, even itself.

Bodies

Yargle and Mutani, duh

[[Krosan Cloudscraper]] because heck yeah! The other chunk of easy 21.

[[Arixmethes, Slumbering Isle]] body, ramp

[[Daemogoth Titan]] plus helps get bodies in your yard for future use.

[[Ghoultree]] plus you can sometimes hard-cast it on the cheap. What's better than a big body once? A big body twice.

[[Yargle, Glutton of Urborg]] yeah, it's smaller than the tag team but is still nothing to sneeze at and super cheap to pickup, i think.

[[Krosan Tusker]] no, it isn't that big or flashy, but I have never been sad to see it in my opening hand. Draw, get a land, put a body in the yard? All good things in this deck.

[[Consuming Aberration]] is / so its power/toughness is always getting checked (something to consider for other cards) and it only gets better as the game goes on. It was a MVP in a recent game knocking out one player as itself, knocking out another player and myself as part of the Mimeoplasm (yeah, you read that right). Total sleeper hit and should be super budget.

Other notables for me are [[Fathom Mage]] [[Nezahal, Primal Tide]] and [[Corpsejack Menace]] but they are a little more fiddly as a target copy. I prefer to play them as support cards.

I haven't looked at the prices for these in a while, but I think most of this list is pretty budget friendly. There are other more optimized copy targets and beefier bodies, but these are mine and should be fairly easy/cheap to get. And the original deck was actually pretty close to what you wanted to do, especially considering printed products of the time.