Secure home bike storage

Hi Forumengers

We have become overrun with bikes and there is no more space for them inside.

We have the luxury of a large covered undercroft, although this is not secure and cannot be made secure.

We are looking at some way of providing storage space for roughly 5/6 bikes which is instantly accessible and with individual locks on each bike.
We were thinking of something like a row of Sheffield stands which were freestanding but bulky. Storage could be wall mounted too.

The ideal would be something similar to what Rough Trade have, but much cheaper.

I was wondering what people would suggest, where to look and if anyone has anything they are not using/want rid of.

Thanks
Tim