This ship has sailed... While, some of these are doing "ok".. This is not like how it used to be. I've been buying and "investing" in this line since the beginning, and the growth isn't what it used to be with many of these. A few years back, sets like Sungnyemun and Burj would net you 4x in little time. That just doesn't happen anymore.
I don't consider a 69.99 set topping 90 a success, when you add in fees, etc. That's a set that you pretty much can only land at BAM or B&N, and so you aren't going to find those half off on a frequent basis. A few years back, you could use a 20 off 100 coupon with a 10% discount at BAM and stock up on these. Now, those type of discounts are gone. I was pretty much the only one at my BAM that bought them out, and I always used the coupons. Now, they exclude lego. It was a great ride while it happened...but the loopholes are closing, and too many people jumped in. The 25% off + 10% discount at B&N deal was decent recently, but I don't see any of the latest retirements hitting 4x, let alone 3x anytime soon. Now we cheer when a set barely goes to 1.5x.