Hi, Frank -
According to the serial number, I'm guessing it's most likely 1997-98. It looks to be in very clean condition with all original components. I would say it could sell for anywhere between $1700 and $2250. There are a lot of X-150 and X-175 fans.
One factor that may affect value, in my opinion, would be what pickups are in it. You may want to check out
GAD's pickup guide to see if you have Seymour Duncan SD-1s or the Fender HB-1s. IIRC, Fender started Guild HB-1s with SD-1s by the end of the 90s. Many tend to prefer the SD1s over the Fender HB-1s.
I'm sure that more experienced members might have accurate insight into this. My preferences lean towards the Florentine cutaways of the Guild archtops.