Agree 25mm size would be better. Michelin Lithion 2 might be worth a look. Saw them online somewhere for under $30. That's a lot more than $12, but if they last twice as long, the cost is reasonable.
I've found that the rear tire wears much faster than the front, so that replacing both tires when the rear is worn out is a waste. Generally I buy tires in sets of 3, keeping the front on the bike through two rear tires. When the second rear is gone, I'll change the front even though it's not worn through, just to keep fresh rubber up front for safety.
Another way to manage tires is to rotate the front tire to the back when the back is worn out, always mounting the new tire on the front. This method ensures you always wear the (rear) tire out before replacing it, and might be more cost-effective than my scheme, but it's also a bit more work.