can u just plug in an imac in the philippines on the wall without a transformer?
i used to live there and remember having to deal with transformers.
and to answer your question, ssd BTO is too much. after-market is the way to go and since you're a tech, it should be a breeze for you to do this and if you're worried about voiding warranty, then i would just hold on to the original hdd and put it back in and cross-fingers that apple or 3rd partry techs will overlook the fact that you might have taken out the original hdd. i think that the only way they would know that you self-installed an aftermarket hdd is if they are super stringent inspecting the adhesives that are needed such as the temp sensors, etc. that will lose it's adhesiveness once you take them out the first time. but, then again, like you've mentioned, a techie person wanting ssd is a different story.
after-market ssd's will also not support trim for some reason. but, it's not stopping anyone else from doing this so i think the trim support issue is not a big deal or they might have hacked it to support trim via some other way.
i think the easiest way to keep warranty and have ssd in imacs is the BTO. it's easier to put ssd's in the mac pro's, mac mini's and macbook pro lines. but, the imac is harder without obvious warranty-voiding steps. but, the imac already has fast 7200rpm hdd's that an ssd is really just an enthusiast option. not for mainstream.
the 27" imac will support a hdd and an ssd and an optical disk drive. but, i think, the 21.5" imac will only have space for an ssd if you take out the optical. either ways is a chore, which is why i mentioned BTO is the easiest way but at a premium. unless, you just wanna do a simple swap. i think there are threads for this if you search it.
update: just checked the apple store and it looks like there is a BTO for a mechanical hdd and an ssd for the 21.5" imac. so...