PCGS has the 1890P listed at $33 in MS62 $40 in prooflike MS62 and $100 in deep mirror.Of course you'll probably have to pay a bit more from a dealer,especially if it's slabbed by one of the big three. according to PCGS: The 1890 Morgan Silver Dollar is common in Uncirculated conditions, but scarce as a Gem. The most "common" Uncirculated grade is MS-63, followed by nearly equal quantities of MS-62's and MS-64's. I personally would pay $45 -55 if there aren't too many bag marks on it.
It would not be wise to ever put much faith in the values listed on the PCGS site. They are often too high by 50% and I have seen them be more than double the actual value. The 1890-P Morgan slabbed by one of the top grading services as MS62 can easily be purchased for $25.
In life one can not expect to always get the best price. The trick to success is not to ever, ever pay the highest price. You done well, next time you do better. Remember GDJMSP is one of the masters of collecting and it will take more then a few years to get to his level.
Look around on ebay...on their ended items...and see what they have been going for. That would be the best way to find out. Speedy
First of all - what Speedy said Some have paid more - some have paid less. But in today's market $175 is a better price