B&H Photo-Video offers
the Pentax SMCP-DA 50mm f/1.8 Standard Lens
, model no. 22177,
for $76.95 with free shipping
charges the same, although it's currently on backorder.) That's the lowest total price we could find by $23 and the best deal we've seen for this lens. It features a dust-, water-, and grease-repellant coating.
Update: The price at B&H Photo Video has increased; however the offer is still available at Amazon
with free shipping
. It is temporarily out of stock, but can be ordered at this price for shipping when available.