Return string between two specific characters

[kaytoo]

What is the best formula to return a string between two specific characters?

Ex:
Aasd asd asdf PO#123456 adf asdf asdf
Aasdf asdf adsf PO# 123457 adsf asdf asd $100.00
Asdf asf #123-123458-0C asdf
Asdf #123459
Asdf asdf asdf adsf # 123455-12 $5.00

I want to extract 12345X from each cell.
Sometimes there is a space between the number and #.
Sometimes the number ends at the end of the cell.
Sometimes the number has -'s
So, if there is a hypen at the end of the string followed by only two characters, I want the number to end before the hyphen if there are more, i want the whole strig after the hyphen.