Surely it's cheaper to contract out the 100 Sqn / FRADU role?
Something like this perhaps?
Discovery Air Defence Services - Home
I'm sure if the contract specified AI equipped aggressors then either the rumoured ex-GAF F4s or some used F16/18 or MiG-29 could be included in the mix?
Can't see the capital spend to replace the airframes, but a 5 year contract might attract enough interest.