Value of Heinrich von Arx's water color portrait?

[wfl...@cvn.net]

I have a signed Heinrich von Arx watercolor portrait of a Swiss peasant
girl that is approximately 6x8 inches, dated 1842. I purchased it at a
local estate auction. It is in an (original?) 19th century mat and frame.
The painting is in good condition. My local research sources are limited.
I sent photographs to an "expert", who felt it was authentic. Auction
price indexes are not available locally. Can I access these indexes on
the internet? I feel certain in the circumstances that I obtained it
that it is the real thing. I do not expect to sell it, but would like to
have an idea of it's value, or the range that his work might sell in.
thanks,Bill. e-mail me at wfl...@cvn.net