Since I live in sunny CA the costs of new lowers are irrelevant to me since I can't get one. It appears that from the one post that the diference in value, not cost but value is about $120-140. so he got diddled in the amount of -
Actual Value of Pre-ban Lower ($250?) = AV1
Actual Value of Post-Ban lower ($120?) = AV2
Actual Cost of Lower (What was paid -unknown) = Price
AV1 minus (Price minus AV2)
So unless he paid even more than the expressed value he got diddled for probably some where around $90 at a minumum to $200 (hopefully not more) in any case, unless you can find the seller and and have him make good on the difference in values, chalk it up to a leaarning experience and build a post-ban. Is $100 or so worth taking the chances on? Hell you can blow $100 on a good meal, or worse on a bad meal.
theres a point that you gotta suck it up.
Build it illegal, and sell it = not your problem (probably, no guarantee the buyer doesn't bring you into any problems, the chances of problems are slight)
Build it illegal and keep it = a possible problem, but only if something goes to poop and it gets looked at.*
Build it legal = no problem.
*As noted it would only be a problem if the Feds got it and decided they had a problem with you. Not terribly likely unless you do drugs, threaten the Pres, or you have any of the following who are presently or about to become mad at you (wifes, ex-wifes, girlfriends, ex-girlfriends, boyfriends, ex-boyfriends, business partners, crooked business partners, in-laws) anybody that would drop a dime on you with the intention of getting you in a shitload of trouble. Up to you but I've made a few $100 learning experiences and I move on. (I generally don't let the wife know but then again)