Yea i would say it all depends on how much you paid for the base sign its going to be hard to beat a huge store that has massive overhead but if you can find them cheap it should not take too much work or vinyl to complete. id say make a spread sheet on cost and see if the final profit is suitable to your liking for that low of a price or if you can up the price in your area.
there are alot of vairiables to consider.