Include ECA in the costs, yes? Even though your budget doesn't allow Ghostkershield, it cripples people when they're running against someone with a Defense Boost advantage.
I'm not sure on the actual going prices of things, so I grabbed TP values. The only real question is whether you want Mask of Coltzan or not, since it discludes Dusty Magic Broom from possibility within your cost range (which I would would recommend over Air Faerie Crown). Ethereal Sword is a possible substitute (running Air for its attack)
ECA (3.9)
Mask of Coltzan (3.6) OR
Golden Compass
Dusty Magic Broom (1.3) OR
Ethereal Sword (200K)
Thief Dagger
Leaf Shield
Scarab Ring
Earthen Scorchstone
Downsize!
I'm not entirely certain what range of weapons are being seen, but the Earth defense of Mask of Coltzan would probably be rare to use (Bow of Destiny being the only thing that comes to mind, which will get five Air through anyway, and quite probably its three Fire). On the other hand, I'm not sure the Dark defense in Golden Compass would be enough to spread over a possible ten Dark icons (certainly not if you're fighting 85 Strength Boosters).
Dusty Magic Broom would be the more powerful way of dealing with Light (also getting off the attack), but falls just beyond your budget if you're getting it and Mask of Coltzan. Ethereal Sword isn't going to be blocked except by Burrow, but would be dealing less icons. Thief Dagger would be a poorer substitute, though a consideration (more situationally designed to deal with Scuzzys and Staff of Righteous Fury).
The Shields would be primarily aimed to deal with certain weapons (though if you're using ECA every turn, you'd at least need a species ability to back up a shield for offense). I listed it mostly because it came to mind, and depending on your Freezer preference there might be space left open.
Leaf Shield would deal with Essence of Esophagor and Pike Pike (though it would need to be combined with a Light-blocker to hit Pike Pike).
Scarab Ring is all a matter of if you see any Fire running around. It might not be worth considering at all
Earthen Scorchstone is listed because there's no other way to deal with Air.
Downsize! could be dropped or swapped for something, as its usefulness is debatable in a defensive set.
All in all, mix and match as you please. I'm not good with defense-based recommendations, but I'm fairly certain I listed all the things worth considering given your budget.