I got my setup from Ebay (China Seller) for $9.99 each (free shipping) back in April. I bought 12 sets total. Mechanical Chain Base #01 x2, #02 x2, #03 x2, #04 x2, #05 x2 and #06 x2.
That same seller has some more for sale here.
I can personally recommend that this is an honest seller, has good communication and will get your order processed fast.
For around $120 I have a decent base that is tall enough for even my TFC Hercules to stay in scale and not tower over the top of it. I have 3 floor panels that are still unused, but all 12 side panels got used. I find the 12 side x 9 floor panel mix to be the best look.
I painted mine also. All the extra bits (some of which have to be assembled) got painted bright yellow. And I even ordered a construction themed decal set off Ebay for $1.99 that I used to give it more of a "construction" type feel to the hangar.