Cutting costs to increase profits can actually be very effective, the theory being that although you make less money from each unit, you can shift a proportionately higher number of units and reduce stock stagnation.
I believe the last GW half yearly report showed revenue of £60.5M and a pre-tax profit of £7.7M, equating to a 12.73% pre tax profit margin. Although this doesn't sound fantastic, when you compare it to another company for example BAE systems, a FTSE 100 company who reported £7,952M revenue and pre-tax profit of £529M, only a 6.65% pre-tax margin it looks a lot better. A lot of businesses DO operate on a thin margin, GW's definitely isn't the thinnest though.
To the OP, theres a bit of fluff in an older codex that refers to a regiment that was bought back up to strength through the combination of a Catachan and an Elysian regiment who had both suffered heavy casualties, creating an airborne jungle specialist regiment.
If you wanted to keep it all GW products it could be an option to explore. Mixing Catachan kits (the HW teams and Command squads don't look bad like the older basic troopers and can be picked up on the internet at a decent price) with some of the FW Elysian squads, and the respirator heads and bits they sell to find a middle ground in price.