It seems like your problem is that you run out of mana too quickly, and your solution is be very against buying any items that would fix your problem? Maybe it is worth gimping your initial fight damage, for the chance to stay in lane for a lot longer, and not lose your point perhaps?
If you're running out of mana, you're better off not wasting a couple hundred gold on mana pots every time you go back in my opinion. After a few trips back you may as well have bought a tear anyway in gold cost (they're not expensive), and you'll be able to upgrade that later.
Also it depends what malzahar you're facing, if you're up against AP Malz, you'll do well to get an early chalice for the MR as well as your ludicrous sustain through his dots. An AD Malz will be harder to itemize against, without gimping your mana regen. Rushing a chainmail for your wooglets, before getting your chalice might be worth it. But honestly, I would still just get the chalice first for the MR that his early game puts out. My first two buys as swain would be a tear and chalice. Farm it up to insane qualities, then upgrade to seraphs and get a BFT and Wooglets. You shouldn't be able to take out a competent Malz (dunno why I'm still using this example?) immediately anyway. Once you both hit 6 you can start going in on him, but before that just push the minions harder than he can and control the health relic.