I strongly advise against saving on a PSU or limiting its budget. its the most important component in your computer. I will not talk about the future disability of adding more hardware or overclocking, but you should be aware with unreliable power you will get random slow downs and blue screens, with a chance of permanent hardware damage, even if you can replace hardware later, you might not be able to recover data if your hard failed.
I lost an entire machine with 2 hards (500 GBs of data ;'( ) because of an unreliable PSU. Try not to make the same mistake.