Dedicated digital filter
Such products definitely exist, but it will be difficult for you to find a product which will fit into your project requirements precisely. For an audio frequency digital filters you can check out QuickFilterTech. For higher radio frequencies (>1GHz) Hittite comes to mind.

However, if you need to operate in the smaller 10s of MHz range, you will probably have to do what most people do: get yourself a smallish DSP or FPGA and use vendor supplied tools to generate a filter firmware (all major vendors have those; parametric design with GUI wizards and pictures supported).

In fact, the best (and most often used) contemporary approach for a single chip embedded design may be just this: FPGA implementing both the MCU and digital filter in the same firmware.

Update

Just noticed that you've already got a Spartan FPGA in your project. You can use Xilinx FIR compiler to generate a fixed filter out of the box (and use frequency shifter to do the tuning) or you can research some of the approaches for tunable filter implementation in the FPGA (some are not very difficult, plenty of publications around).