The "image based"
BTC can be emulated by using combining characters: B⃦.
LATIN CAPITAL LETTER B + COMBINING DOUBLE VERTICAL STROKE OVERLAY
The symbol: $ is often universally used to represent money, even when a dollar or peso is not the official currency. For example: earning $. B$ to represent Bitcoin money can also be used as an alternative.
Technically, '¤' is the "other" currency sigil. While "B$" has the advantage that is 7-bit ASCII, it has the disadvantage that it is, quite literally, "bullshit".