I'm not sure where you have the idea that you must LGPL your app. From Wikipedia:
The main difference between the GPL
and the LGPL is that the latter can be
linked to (in the case of a library,
'used by') a non-(L)GPLed program,
regardless of whether it is free
software or proprietary software.1
This non-(L)GPLed program can then be
distributed under any chosen terms if
it is not a derivative work.
From the LGPL license:
You may copy and distribute the Library (or a portion or derivative of
it, under Section 2) in object code or
executable form under the terms of
Sections 1 and 2 above provided that
you accompany it with the complete
corresponding machine-readable source
code, which must be distributed under
the terms of Sections 1 and 2 above on
a medium customarily used for software
interchange.
If distribution of object code is made
by offering access to copy from a
designated place, then offering
equivalent access to copy the source
code from the same place satisfies the
requirement to distribute the source
code, even though third parties are
not compelled to copy the source along
with the object code.
That says that you merely need to provide access to the source code of the library if it's distributed in binary form. Just make sure you're not creating a derivative work and instead are merely linking to the lib.
If you're not content with LGPL, then you could always purchase a license from Novell.
From http://www.mono-project.com/License:
Mono is available to be licensed
commercially if the LGPL/GPL/X11
combination is not suitable for you.
Mono Tools for Visual Studio Ultimate
Edition includes a commercial
license to redistribute Mono under
non-LGPL terms on Windows, Linux, and
Mac OS X PCs for products with volumes
under 100,000 and revenues under $2M
annually. If your organization intends
to redistribute software which embeds
or bundles Mono, but is unable to
comply with the terms of GNU LGPL v2,
the Ultimate Edition may be right for
you.
For other licensing options, contact
us.