If you don't mind buying loose toys for Generations/Universe/Classics some of our members here are selling them $15 a figure - emmai in particular comes to mind right now. I think he has a loose dirge, Acid storm and RTS scourges up for sale...Kal el has a couple more generations stuff as well so yeah hit the sale threads if your ok with loose figures...

Yeah as OtaG said scour first for a cheap MP optimus coz then you'll have enough left over to buy some cheap Gen/Univ/Classics figure here among fellow members so option

1 and 5 ( albeit online meaning local - which saves you heaps on postage as well.

But if your one who likes MISC/MISB figures then option 5 may take a back seat and go for option 1 first - just don't be impulsive and get the first one you spot - look around online. That way you stretch your dollar more.