With orders of $25 or more, Amazon offers the Irwin Tools Classic Series 10" 180T Steel Table / Miter Circular Saw Blade for $8.76 with free shipping. Outside of the seller below, that's the lowest price we could find by $2. It features 180 teeth and a 5/8" arbor.

Note: This item is part of Amazon's "Add-on Program"; it can only be purchased with an order of $25 or more. If you're not spending $25, Walmart offers it for $9.98 when you order via in-store pickup.