Ron,
Personally, I think that 150yo may be a stretch. What I can say from my experience is: rugs with this coloration, design motif, and pictorial landscape, you are looking a rug which is probably no older than ca. 1910 (but could be as new as ~1940). Specific age is very tough to determine without seeing/feeling the carpet in person.
Jilly made notre that the rug has blue weft, which from my experience (given the knot density + design) would be indicative of a Kashan weaving. However, I find it somewhat unusual that a Kashan rug would have a silk pile on a cotton foundation, from this vintage. Knots are somewhat squared (as opposed to elongated)...
Some one mentioned Tehran, I think that this may be a possibility. Although, again from my experience, I'd probably be more comfortable calling it an unusual Kashan weaving.
Re: value- This is a carpet that would probably sell better overseas. Why I say that, is from my experience of the American market consumers are not particularly fond of what has been referred to as "cartoon-like" depictions. On the other hand, in an Middle Eastern market there is greater appreciation and even desirability for the color scheme and motif.
My opinion (emphasis on the opinion- this is very loose number as I have not seen the carpet in person): US, I'd say 3-4K. I would venture to guess Europe or Middle East (not necessarily Dubai though) may be your best bets for market, and perhaps you'd look at 5-7K. This is all assuming that this carpet is in perfect condition (i.e. No powdering, No low areas, No cuts/splits/tears/damage/dry rot) As if it were just cut from the loom...
Keep in mind these are prices that it might take a while to sell the rug at, as the market is soft everywhere.
As always I recommend input and insight from multiple sources (preferably when the carpet can be seen in person).