it's possible to play 20 cards other than KC's three times, using a KC chain starting with a TR. so you can reduce cost by 60$, by playing all processions three times on BoMs and Bridges. If you set X=61, you then have BoM at 6$ and Bridge at 5$ and can still get all 10 bridges out of the trash, and some BoM. you can then follow the original plan... but you don't have the KC anymore, so you can play cards onlyl twice. Play BoM 7 times, then bridges 20 times, highway 10 times, princess once. that adds up to
60+7+20+10+2+1 = $100
this can probably be improved though, by moving procession up a layer. I had KC on the first layer of the chain, Procession on the second, and the bridges/band of misfits on the third, but if you also procession some KC's, you can gain them from the trash and play some more cards three times.
there's also a problem with how many cards you can even gain from the trash though.