I would wait and see. If it is just a sebaceous cyst, it should pop on it's own. Put a warm wash cloth on it to help draw it to the surface.
If it's not, you need to have it examined and removed and sent out to see what it is. It shouldn't cost more than $300.
And by the way...I find the statement of "the potential cost of anesthesia and surgery cost almost as much as the dog" revolting. I have almost $5000 sunk into the knee of a $75 pound puppy.
Seger vom Sitz von der Hose
Forever loved and missed.....Banshee