Price wise it'll be roughly the same, although if you do it in stages you'll have to pay for alignment twice. I'd save up and do the lot in one go.
If you need any advise or prices, let me know. We've done quite a few 350s (including my own 350) and just finished an RX7 - makes a great improvement to handling. We can get most brands (Superpro, Whiteline, Powerflex, Hardrace etc) but prefer Superpro