Future Tank upgrade question

[oKrazyii]

I'm looking to upgrade my 29-gallon long tank to something larger in the future and am curious about cost-effective options. Would it be feasible to purchase an all-in-one (AIO) tank and later modify it to include a sump, utilizing the existing overflow box? I'm aiming to save money by purchasing components gradually for the sump.

 

[tzabor10]

Most cost effective solution is to pick u a used unit from someone who is getting out of the hobby or moving.