Iprefer,

I will try to address your answers individually.  Welcome to the boards, by the way.

A) I can't tell you the price differential for Synvisc because my copay is only $5.  Most insurance companies will cover it, but the cost depends on your insurance.  Cost for PRP will likely depend on where you live, but here in L.A., it's overpriced, just like everything else.  PRP runs about $750-800 per shot, per knee.  The Regenexx version, called SCP, is more concentrated and around the same price.  I don't know about HGH, but regular prolo is usually around $300 a shot.  Add some money on top of that for the HGH or Testosterone Suspension.  Also, I don't want to get your thread closed, but there are guys on this board that actually have been injecting themselves.  If you've got elephantitis of the cajones, you can check into that as well.

B) Every procedure's success is seemingly based on the individual's response.  I've had prolo with D50 and lidocaine and achieved great results...until I got overly aggressive with the activity and made myself worse.  The key is that, if you're going to pursue these alternative modes of therapy, you also have to be patient enough to let them take hold.  I'm also s/p stem cell injections and PRP, so you can follow my thread to view my progress if you like.  I update every 1-2 weeks and add things when I feel they are important.

C) Allegedly, the stem cell procedure is supposed to be the most successful, but if you're not ready to shell out $7-8K all at once, you can go about it a few different ways. 

  First, you can check Synvisc.  It might be cheaper because of a copay to your insurance company.  Keep in mind, however, that Synvisc
  doesn't really fix anything, just masks a problem for a variable amount of time.  It lasted only 3 weeks for me.

  Second, you can start off small and go strictly prolo with D50/Lido.  You might also be able to add the HGH into your therapies.  The straight
  prolo will create joint space for you and strengthen the ligaments around your arthritic knees.  This might be all you need.  The HGH has
  properties which may allow cartilage regrowth, but it will cost ya more. 

  Next, you can look into PRP.  You can obtain benefits of stem cells via PRP.  Regenexx has a version called SCP.  Their lab process is a bit more   
  meticulous than most and they claim to gain a higher stem cell count as a result.

  Stem Cell injections would be the next step.  Pricey and like everything else in this course of treatment, takes time to truly see results.

D)  I think if you wanted to cycle, your role would likely be reduced.  I currently cycle on a stationary bike for 40 minutes at Level 1.  You don't want to put too much load on the cells, but you do want them to work and stay active.

There are more knowledgeable people on this board that can help you, but hopefully, that can get you started.

*Side note.  From what I understand, you MIGHT be able to get your insurance to float the bill on some of this stuff.  I have talked with a woman who has Kaiser insurance who got her ortho to say PRP was necessary and since Kaiser didn't offer it, they were on the hook for the bill.   I wish I was that lucky!