Lots of BT players use Mechwarrior: Dark Age clicky infantry and battle armor for their battletech games. With BT infantry figs having crept up to around 8mm, the 10mm scale figs don't look bad at all and it's nice that they are representative of real BT units. You can still find mixed lots of the stuff online and if you put up an ad in the market here I'm sure some folks would have some to trade you. Most folks who were into the game ended up with alot of unused basic infantry. Each base of 3-5 used to be availalble for 30 cents each online. Some of the aircraft and vehicles for MW:DA work well also, but you'd want to be a bit more choosy with the vehicles.
Also, if you want cheap hex bases for them, EM4 sells 25mm hex slottas 20 for 1gbp, and 30mm raised-edge mech style bases 10 for 1GBP. Proxie also has 30mm hexes with a bit of texture on them for a price in between those two.
This pic here shows them on one of the 25mm EM4 Slotta hexes. The mech and tank are Mechwarrior clix 10mm figures and for height comparisons, each floor of the building they are in front of is about 15mm tall.
They stand a bit tall because mechwarrior infantry come attached to a blob of earth. They can be removed from that, but I didn't bother. Once I cut the blob off the clicky base I just glued it to the base and smoothed the edges with my "Magic Mud" (housepaint with alot of pummice paint texture mixed in).