WAVE 42! I have no idea how I actually managed this one. But it happened. Apparently this a pretty good score? Okay, so I found out some nice tricks. In order of what you need to defend against, here is what you need to buy in order (Slight changes based on what the announcers say will be next, i.e a clone for jetpack bots). Buy a clone around Gold Tier, if you die before then it isn't really worth it.
Deflect Arrows I, II and III
Jet Pack
2 Energy, 3 Energy
Clone (Buy the round after you die as well)
Kick and then Get Up!
Bow
4 Energy, 50% Energy Increase, 100% Energy Increase
Arrow Width I and II
Unbalance I, Good Form I, Good Form II, Unbalance II
Buying the second jetpack is worthless (A green jetpacker has never actually caught up to me when I've sped away) and I've found it actually even messes you up (you'll go too fast into saws), so avoid it.
Use your bow to rapid-fire at any Spidertron 6000's at the start of a round. In fact, don't use your sword on them at all. They don't appear until Wave 11 (Diamond) so you can put off buying the bow for a while. In the level with tons of saws in front it forces the sword-bots to come to you, allowing you to easily pick off those who make it past all the saws. You can then deflect at the archers, winning without barely moving!
Here is proof of my aforementioned feat - I took a picture on my phone. Jocelyn Sharp is a champ! She had a good last stand but she lost to a green jetpacker who killed his friend just to get me. These bots are dedicated! I got to Wave 20 before dying for the first time, and from there I only died to the occasional lucky swings of those green jetpack bots (They are EVIL! Your only strategy is to jetpack straight at them and hope you don't die). I have no doubts that were I to get lucky enough using my current strategy I could reach wave 50 or even 60.
Is this the highest score anyone has ever reached? I want to know if anyone beat this.