Help: Creating a Stable Wireless Network for Home

I have been having problems with my current router the Belkin Play. I have recently purchased a few new products that fully rely on wireless and can use quite a bit of bandwidth, this is causing troubles with my router as I already have a massive amount of devices connected.
I was looking for a solution to make it more stable, I don't mind spending some money to fix it up.

What setups and products could you recommend to make my home network more stable?

Thanks!