This is a tough question! I asked my dad, and he said that neither one is technically wrong. It is more common, in my opinion, to say, "than buying a new one". It is not wrong, however, to say, "than is buying a new one." But, he did also point out that you need to have the first "is" in there, so you have to say "procuring a used car is..." I hope that makes sense! Basically, either is correct, but again, my opinion is that "than buying a new one" is more common, as it sounds less redundant!

You saw a sentence ... or you read a sentence. It is better the way you rewrote the sentence. It is a bit unusual to call the purchase of a used vehicle a procurement. Procurement processes can be lengthy and complicated. Private individuals buy, sell, trade, and barter used vehicles daily in the USA.