The real crazy thing is when you can pile the Golds, Silvers or the Coppers.
Silver is actually easier to pile than copper:
Masterpiece, you can pretty easily empty the silvers if you overbuy by 2, 2, 3, and then 5 x 7. 15 or so turns to ~40 Points AND being a province per turn after that is pretty insanely good. An astute opponent will deny masterpiece buys AND not deplete the pile ... but that is likely a 12 VP swing for giving up a province and you can be more selective (particularly if you want till $6 to start overbuying).
Raid can also churn pretty hard, pretty quickly, particularly with trashing, sifting, or terminal draw to jump start. Averaging 3.5 Silvers per turn is only about 14 turns and you attack your opponent every turn.
Trader - much harder but a few setups can work out well, most notably the Tr family and Peddler as a 2.7 ish card combo. Burning 5 Peddlers is a huge pile of VP and reliable buying power. A 2.3ish card combo is Trader/Feodum which is more reliable and flexible. Trader and Embargo is challenging, but can setup a fast enough payout to win on some boards.
Page is not completely reliable, but you can stockpile Thunters until your opponent gains a large number of cards and then pile for 40 VP.
Generic Silver gainers need to be played 40 times (give or take) and while possible, this is less commonly viable. A few shots that might work are:
Kc/[Scheme or Scav]/Silver gainer (B-crat is fun).
Kc/Cost reduction/+buy (high efficiency like Squire or multiples)
Procession/Trash diving/+buy
Gold gainers are limited, but you can actually gain the lot in one turn with a big Kc chain (e.g. Kc/Explorers)/
Copper, well more VP are possible but it is harder to churn that many gains before game end. Obvious candidates are Beggar, Cache, Sqr, Tfair and Banquet.
Banqueting for copper is going to take 20 turns and that is far too long. Banquet for something with +gains (e.g. Market) might drop that a little bit, but most often you will want a lot of synergy.
Beggars need to be played 20 times and that is just far to long.
Tfair is generating 120 $ and is far too slow along.
Cache will run out long before you make a dent.
That said, you can line up a few select combos for huge cash. Chouse/Tfair should just go for coppers with tower out. Herbalist/Pstone/Tfair may also generate enough cash to buy down the copper.