OK, here is the situation. I am an idiot.
Now that we've got that part over with, basically we've imported 8 PSUs from Korea that looked to have a good combination of cheapiness and reliability for current and future use at the office. Yes, I was the recommender. $25 for each of these seemed a pretty good deal before today.

The big blunder, here, is that I never really made sure these PSUs could take both 110/220v. The things arrived today after a month of waiting (they came by ship), and these PSUs would be perfect for Asia or Europe but this is an American island and we only use 110v. The PSU label says 200-240AC, not 100-240AC... There is also no separate switch.

We called support to ask if there's anything the end user could do to change the voltage to 110v, and they just gave us a list of their other products that can take 100-240.

Is this something a guy with no engineering or related experience can do? I mean like changing this thing from a PSU that needs 220v input to one that takes 110v input? Are there some easy parts I could get that I could replace on the board itself? I've already opened up the PSU case, and still have no clue. I did some soldering for car speakers back in high school. Will that help? lol. BTW, the PSUs are ATX 2.2 compatible.

I could also upload some close-up shots tomorrow if needed.

Out of the question at this point are:
1. Buying transformers (they cost more than the PSUs, so this is a last-resort option)
2. Returning the products for refund/exchange (shipping costs and time.....)
3. Just plugging it in (we tried it on an old PC and it won't boot)

Well, as far as I know those PSU wont work at 110V at all.
I would return them for refund if it's still possible.

Build your own!

Of course, my suggestion wasn't serious, just in tune with the request for "true geeks" help :P

Pretty much this is right on. If the thing isn't made to deal with the voltage you require I doubt there's any part in there you can magically unscrew and switch the setting.

Could you jury-rig something? It's possible. Would your insurance cover your ass if you burned down your place of business or hurt someone? Er, dunno.

IMO, suck it up and return them. If it's a net loss to return them or a wash, donate them to someone who can use them or recycle them. According to your post you're only in for about 200 bucks plus whatever you spent in shipping. While I don't want to imply 200 bucks is nothing, it's relatively little compared to the cost of your other equipment.

Well, thanks, guys. I get the point. Messing with the PSU itself is not going to solve the problem. And neither is 'building my own' transformer going to work. :)
This is just going to cost $$, I guess. Aye, I wish that'd be feasible but since it'll take another month for them to receive the things...... :-P And I definitely do NOT want to lease airplane cargo space to make a return. Meh, Newegg is not an option here because they only ship UPS, and the last quote we got from UPS was $3,000 to ship a 32" LCD TV from San Francisco. LOL! UPS guy freaked out and told my brother to just ship USPS.

These PSUs are also supposed to be more like Antec-quality at Rosewill-prices (dual 12v rails at 18A each and #8 on the Korean geeko sales chart with good reviews), and definitely not at all like the 15 eBay ones that we'd ripped through in the last few years -- hence the big big disappointment.

I guess the options left now are to try to sell these off to people with transformers at home and/or to buy some transformers and actually use these for years to come. Yup, that's about right. $200ish plus 5% import taxes and really not much in shipping since the whole shipment's shipping cost before tax was $80. It's just that the trade company doesn't charge that much less shipping for bringing in 1 box vs. 10 boxes (some kind of quota issue with their contract with the actual shipping companies).

We'd all been really excited with this shipment because we finally upgraded CRTs to 23" LEDs, banged-up keyboards for new ones, and had all the parts to replace our main workhorse computer from a P4 to an E620. Every single component turned out to work fine except for these. MAJOR BUZZKILL.

Thanks for helping me crossing out dumb ideas, though. You guys probably saved us a lot of anguish and probably many hundred $$$. :)
I'd like to mark all your replies as solutions but since I can only choose 1, I'll choose satoru's since it was really long and detailed.