I'll play your devil's advocate among this crowd. 150 LP's is not exactly a massive collection, though what they mean to you may be an entirely different story. I sold my turntable rig that I'd had and upgraded several times since 1985. I tried and tried and just never got what all the fuss was about. OK, yeah, it sounds marginally more musical than the better digital, but it just wasn't enough for me to go through all the expense and trouble of cleaning, maintenance, pops and clicks, short play-time, etc. My collection is over 400 LP's which I still consider small compared to many I've seen. You can always get a great deal on a table like yours here on A'gon if you decide you just can't live without it. I don't agree that they'll be commanding a high $ amount....there are always good deals to be found if you are patient. Analog (turntable) is of the most esoteric of music playpack systems at this point, and is being relegated to hard-core audiophiles more and more. I don't see that changing any time in the future, any more than I see silver film emulsions making a resurgence over digital even though silver is clearly superior. I don't think it is going to die as a format any time soon either, but I also don't think it will flourish in the mainstream ever again. Precious few new releases are available on LP, and that number will only dwindle with time and as digital closed the gap (and I'm sure it will). The one great aspect of turntable ownerhship is that buying old LP's is oh so much more affordable than new releases on digital (which are a complete rip-off at today's prices). Regardless, if you're not using it, and haven't for some time, I'd say sell it. As Satch suggests; to get an idea of price, just search the current ads.
Back to your LP-loving A'goners. No need for flames, I know mine ain't a popular opinion here. Just one among many....
Marco