Robotech kits? Where can I find 'em?

Try Ebay (I got a few from there) and also check www.hlj.com They have some newer kits from the Hasegawa run of the VFs. Also they have Bandai kits if the Battroid forms. But remember -search under the 'Macross' name.

Some of the kits you are looking for are the Destroid Defender (Rifleman), Destroid Spartan (Archer), Destroid Tomahawk (Warhammer - my personal favorite), Destroid Missle Phalanx (Crossbow) and the Tactical Pod Glaug (Marauder). In the past month I've found all the above on Ebay.
I haven't found out where the Battlemaster came from but if anyone knows I would be very interested in finding out!

Battletech 'borrowed' the designs from the Japanese series Macross, Dougram, and Crusher Joe. Your best place to find them is Ebay. Type Robothech model in the search and you should be able to find a few of Revell's versions of those mechs from Macross and Dougram. You'll have to look for the original Crusher Joe stuff seperately.

Depending on the scale you want, expect to pay pretty high prices on ebay (at least for the 1/72 stuff). I have a Battlemaster still awaiting construction and would love to complete my Heavy Lance with a Warhammer, Marauder and Rifleman but just can't justify $70-100 for them.
Most of the mechs are also available in 1/100, 1/144 and 1/200 which you can find a lot better pricing.
Good luck on your search and if you find someone with a few extra they want to part with in the $20-30 range (or trade for ST stuff), let me know.

You could try looking out for Exo-Squad toys. They released a few Macross toys that were in 1/72. Cheaper, but not as nice as the kits.