How to economically clean old records

I recently took possession of my father's record collection which has some gems, but many are over 50 years old and weren't cared for particularly well (some dirty, some scratched, some both). I am wondering what is an effective and inexpensive way to at least clean the surface of these older records that have never been cleaned even once? I am afraid to use my regular cleaning brush and fluid system for this purpose for fear it will shorten its useful life.
Try this method. It works remarkably well on dirty, grimey records. If, however, the record is scratched, nothing will help.
For me, the other half of the equation is a bundle of deep pile microfiber polishing cloths. I got a bundle of 25 16"x16" deep nap microfiber cloths (9,000 naps per sq. in.) from Sam's Club for $10. Add a handheld steamer from Walgreens for $30 and you're there (though I also use spray-on record cleaning fluid from a local used record store as well).

Put a microfiber cloth on the kitchen counter; put the record on top of it; spray on some record cleaner, run the steamer over it, use one cloth to wet-wipe and deep scrub it (the microfibers get deep into the groove); steam again to blast away the residue, and then use a third, dry clean microfiber cloth to wipe it off and dry it. Flip it over and repeat. Then put it in a dish rack to air dry.
The age of the LP's is not a problem. I have hundreds that old or older that are in fine shape.

Your description of their care and condition is not encouraging however. As Calbrs03 said, scratches are non-reversible.

So are other types of less visible damage. LP's played on inexpensive or poorly set up rigs tend to be damaged by the mere act of playing, even if carefully handled. None of the LP's I had as a teenager is listenable now, even though I handled them more carefully than most of my friends. My "kid's" rig was destroying them, though it took better rigs and systems to reveal it. By then it was too late.

Clean a few that interest you and play them to see how it goes before spending alot of time, effort or money on cleaning the whole lot.
Disc Doctor Disc Doctor Disc Doctor Disc Doctor
The steam cleaner and the microfiber cloths are both helpful, inexpensive cleaning aids. If you have the budget, a cleaning machine such as the Disc Doctor or the entry-level Nitty Gritty machines are well worth the money, particularly when it comes to cleaning old LP's.

You will still need a good cleaning solution, no matter what cleaning METHOD you use. I have used the following cleaning solution for more than 35 years with very good results:

1. 1 gallon, less one pint, of distilled water
2. 1 pint of 99% pure iso-propyl alcohol (NOT rubbing alcohol), added to the distilled water
3. 5-6 drops of a good surfactant, which acts to break the water tension so it spreads evenly on the LP (I surfactant from a lab chemicals supply firm, but I know some guys who just use liquid dish detergent).

The key to getting your LP's clean is to get the gunk out of the grooves and then REMOVED, which is where the vacuum-operated cleaning machines excel.