Bruce,
Buy a top quality 2 72" Grinder with a variable speed motor and at least a 1 1/2 motor.
I have used a been extremely happy with a Hardcore Products grinder with with these motor and controller spec's for over 13 years. Mine is milled aluminum. They now have a cast aluminum version that I would buy now.
http://www.trugrit.com/
I would pass on the Kalamazoo and others in this price range, I think they are made in china now.
I own two other machines and since I don't wish to say anything negative about them here I will just say, Only Cry Once! Buy a top quality grinding machine and then build around it. The other's worked, but by the time you do all of the up grades you really need you will be close enough in costs that you are better off buying a top grade machine that you can use out of the box with out any compromises.
Ever if you wish to forge your blades, You still will be grinding for final shape and finishing & handle sculpting.
The jig saw will hold you for now buy your knife handle cut into scales.
If you really want to equip the whole shop for that four grand. A good less expensive grinder that I started with and still have is a 2 x 72" by Norman Coote.
http://www.cootebeltgrinder.com/
You can put together a Hollow and flat grinding machine for around $1000.00
with variable speed etc.
That's my 2 cents on getting started in knife making.
Enjoy the fun! If you worked on the wood & metal of rifles you should be making great knives soon.
Laurence
www.rhinoknives.com