I am pretty sure that router does run dd-wrt it was one of the most popular back in its day for that reason. It is just a matter of finding the software that is compatible out of that massive list you have......that tends to be the hardest thing on dd-wrt actually loading it is easy.
Unfortunately I am not the best person to recommend a affordable commercial router. I only work with cisco and juniper enterprise level equipment...and inexpensive is never associated with those. I personally use a Cisco 2821 for my internet router but it is a very old model which makes it less costly. It also is not all that fast, it will likely not run 100m internet connection. There are of course more modern models but you quickly get over $1000...