Well I've tried Staminus and Awknet and they both just seem to rate-limit if I get like 300MBIT SYN, is there any provider that won't just rate-limit but will actually filter the attack for around $200/mo?
To be quite honest if you are looking for true filtering at such a level you would need some form of hardware firewall which can do SPI and other higher level filtering techniques. In addition such hardware tends to not come cheaply. I'd strongly suggest you raise your budget a bit higher if possible as you may have better luck finding a reliable solution.
The other option is to get a decent grade server and 1GBit port to the network you go with (so you can filter on the box itself). The issue here is you'd need to be sure the provider isn't going to charge you for incoming bandwidth in the event of an attack.