what are the cheapest ways to pave a 170feet gravel driveway, no local restriction apply.?

I agree that chip and seal is usually the cheapest. You will have to remove the gravel first and have a good grade.

Some paving companies will have recycled asphalt even cheaper.

Or you could do like a Friend of mine. He just bought a truck load of cement in bags ( not concrete mix ) and used a lawn spreader to apply to the gravel then turned on the sprinkler. It is still very rough but that is what he wanted for when it snows or is icy.

Chip and seal,used to create quite a few rural roads,is a combination of limestone "chipped " to 1/4 inch stone or less and oil "seal". Both are very inexpensive and settle fairly firm.

Good Luck

I would think asphalt < but you also need to consider maintenance cost as well. Call around and get estimates.

put a layer of crushed limestone on it .

spread Portland cement [powder] on it, sprinkle it with water,