Ask REI when their next "garage sale" is. This is a quarterly event when they sell the items people return that cannot be sold as 'brand new'. Many of the items are returned after less than a week of ownership for rather mundane reasons (not my color, didn't fit, etc). If you get there early, you can get some great deals.
Other possibilities include Go-Lite (they have a brick/mortar store in Boulder now), as well as Eureka! (not sure where to see them in person but they get good reviews for their price).
If the tent does not have a bucket-type floor in which the floor continues up the wall 4-8", you'll need to seam-seal it - and it's not a terrible idea to go ahead and seam-seal the entire tent. This is not something you want to do during your first outing, do it at home ahead of time on a dry breezy day.