You've sort of answered your own question :-). You're saving up for something. If you spend it you're no longer saving up. 

There's no right or wrong answer here, it all depends on what you want more or what outcome you will regret more. That said, I think you're likely to see the hornet implant in the shop sooner than you will see a mech CRE repeating (in case you miss your desired CRE one time). So, IMO, there's no rush with the implant.

i got implant for something and next came deathwalker and i missed it :) so idk.. i sort of regret it :)