Not sure if this is cheap to you, but the SA Manta is pretty bad a** and is $170 brand new, the same price of some single pedals out there right now. While the Manta is a single pedal, it has two footswitches that can store two presets and has a TON of filters and could do what the DOD does and SO much more. I astually used to have the FX25 and did like it. But now that I have gotten a Manta, I will probably never need another filter. Ever. I lost interest in filters for years but the Manta most def sparked my interest in them again.
As Jumble above stated, the 60b is also a great alternative. Has so many, very usable and very fun, filters, delays, reverbs, auto wah, amp sims, dist/OD/fuzzes, octaves and synths to have hours of fun with. I do indeed have the most fun with the synths in the 60b myself.