I've heard of people doing budget challenges, but it still requires a playgroup of sufficient size where it's worth spending $20+ on a deck specifically for that playgroup.My only real thought around trying to reduce spiking in an "open" format (i.e. not cube or battle box etc.) would be to maybe have some concept of forced rotation. Oh you're playing a bunch of expensive powerful cards? They're now banned or restricted! To encourage constant brewing. Maybe the cards get unbanned after a while (maybe on a league basis?).
Spiking is inevitable in a game where there's a winner, but you can change the context if you don't want to buy a $500 deck. That's why I bring the whole format with me.
I should also say that Jumpstart is really cool and would probably let me play Eldrazi more successfully, but I enjoy drafting more than playing.