With a little heat, you could bend them yourself.
Most plastic supply houses can do it in-house, but you'll be hosed with their cost.
We just bent about 3 dozen signs for a longtime customer. Get a 36" heat strip and you could do 3 at a time. They take maybe a minute to heat and bend, so that would be like 3 a minute if you continually change them out. maybe 2 hours for you.