It's already a fairly small village hall I'm using, I'm not sure we can get much cheaper unless it's someones double garage. But it all depends what we are bringing - if we're bringing a straight 4ft plain track board then we won't need much room, or stock, or time. However we've got the possibility of two fiddle yards, two layouts (one through, one terminus) and a couple of intermediate boards, plus potentially some curved boards which I am going to be making which will eventually attach to my home layout as part of its "larger form" for exhibiting, whereas in the shed I'll simply be using setrack R2 and R3 curves to make it fit the space I have available but as it's all being built to the Dave standards they will be usable as modules in due course. We will also need a junction, of some form, in order to add in some route options and give things a purpose.
But once we are confident we have enough to go ahead (and let's face it, we are getting there with every chance that people will join us along the way) we can then see what modules people are offering and see if anyone is prepared to build an otherwise "not needed" plain track straight or curved board in order to give us a longer run. If we can make an S shape in the hall then we could have over 100ft end to end at least given sufficient modules, perhaps more if we have junctions and small self contained little projects.