Effects Unit

Hello, i'm finally close to finishing my new cdj setup where I won't be using a computer. Two CDJ-700's and a Denon DN-X300 mixer (yeah its old, but gets the job done). But I was also wanting an effects processor to add alittle spice to my mixes since the 700's aren't that great and the mixer doesn't have any. What would be a good one to use without destroying my bank account and would it even be possible to use an effects unit with my mixer? Input greatly appreciated

I used to have the x300 and used the send/returns on it to hook up a kp3. Worked really well!