need a regular expression hint

I am putting the finishing touches on the new formatter, but I need to figure
out how to do a regular expression that will match each of these strings:

r'$10$'
r'$+7.3567{\times}10$'
r'$-5.740977777{\times}10$'
r'${\times}10$'

Here is my attempt:

re.compile('\$([(\{\\times\}?)\-+0-9]+)\^\{(-?[0-9]+)\}\$')

Could an Regular Expression Guru please have mercy on me? My head is killing
me.

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--
Darren S. Dale

Bard Hall
Department of Materials Science and Engineering
Cornell University
Ithaca, NY. 14850

dd55@...163...