Looks like a low-pro "funny bike" made for time trial riding. Probably takes a 700c rear wheel and 650c front, but hopefully the seller can tell you for sure what wheel sizes are required - or failing that, Gilmour is still making frames and could probably say: Gilmour Bicycles.

So what's a rough condition, low-pro frame worth? Even knowing that it was custom built by a particular framebuilder, I don't think it has much cash value unless there's some kind of sentimental value to go along with it. Half the value here is in the stem, bars, and levers. If I had to put a number on it, $100?