I like FJetter's response. I think an IPC and just getting back into that would help you. $500 for a DPE? Yikes, that's about $150-200 more than we pay here.

Are you currently an active CFI and flying often? If you are, then I doubt it's going to take 20hrs. Just seems to be overkill unless you honestly have completely forgotten instrument flying.

When I was an active CFI, I did the min 3hrs in 60 days with my co-worker, he signed me off and off to the races I went. Easiest check-ride ever, but I was instrument current.