If an iron has a cast, as opposed to forged head, can they be bent (lie angle adjustment)?

Yes. But, a clubfitter may have you sign a waiver in case of breakage. Often times, you are better off sending them to the OEM to have it done. I saw you are considering Callaway preowned. They will bend them to your specs, it's right on their website if you hadn't seen it.

Divots, thanks for the input.
I've already talked to Callaway and it's actually very cheap to have them do it (so if I buy from them, that's definitely the way to go). I'm a little unsure about TaylorMade...some of the 2 year old models are showing up on Ebay, but they are cast heads.

Aimee,
Taylor Made is great about such requests. They do it for free. All it would cost would be the shipping charge to them. They even pick up the return cost. I called them just a couple weeks ago to ask them about changing the lie angles on my new TP wedges. I didn't even ask if THEY would do it, just if it was possible and to ask what metal the heads were made of. They said "Oh, we'll do that for free. Just take them to a store that sells Taylor Made and have them contact us to arrange it free of charge." I thought that was pretty cool.

That is pretty cool...never hit the TM's at the range, only indoors vs. Cally's which I have hit at the range.
I just spoke to someone at Callaway preowned (it is $20 to bend the whole set)...they have a set as I am looking for, just need to have the lie angle changed...very good condition (which is almost new, from my experience with them). I think the prices they are showing online include that 15% off sale. Plus we have some old Cally's in the basement that they'll take for trade-in value...
I curse you, Divots, for making me look at these again, now I may just have to buy these irons! Wish I had more money to be a real club 'ho !