Generally swiftness pots and free action pots sell well... in addition to that... I rarely ever put healing or mana pots up that don't sell (if priced reasonably). You may be able to find a market for other things like agi/str elixirs, stoneshield pots, etc... as you level. I can't really comment on that because I leveled alch 1-300 after I purchased my epic mount at 60. I didn't really spend much time at the low end selling pots - but like I said I do always put my lower level healing/mana pots on the AH when I find them (say by running SM or something like that for gold).
Pre-BC, while guilds were raiding, you could sell pretty much any and every major high end pot without a problem. Mongoose, giants, major hp/mana, all sorts of resistance pots, etc... I suspect it'll be the same way at level 70 when you get there (though I have been mostly creating pots for my own use - not selling many currently). While you wont be pulling in huge amouts of gold selling a few pots, it's very hard to saturate the market, and there is a constant demand which is very nice.