Is It Time To Sell My Vinyl Rig?

  So let me get this straight, you are saving up for surgery to have your anatomical structure removed to sell on consignment at a gallery?                     

I would put off that ingrown nose hair procedure for a while and keep enjoying the music!

You already know the answer.

sell the analog rig

Is this to fix your goofy foot?
Sorry, could not resist, and I do hope the surgery you require has nothing to do with any life threatening situation. If the condition IS life threatening, you don't need our advice.  You need to move forward.Your LP collection is downgraded in value for being all mono LPs, unless you own some of the most sought after mono LPs, e.g., the Beatles on Parlaphone, or something of that ilk.  You might consult a reference, like Goldmines, to determine what you can get for the LPs.  Otherwise, I would guess $2 to $5 per LP, if you can find someone who wants mono. The cartridge likewise is worth very little, and the turntable/tonearm is worth several hundred dollars at most.  By far the most valuable item in your vinyl ensemble is the phono stage.  Figure 60% of its retail cost.
Finally, I hope you do recognize the lack of logic in saying you prefer your digital source to your analog source, when all your analog listening is in mono. And your mono cartridge is very.... basic.

"Will I regret this afterwords?"

It depends how successful the surgery is.