Buy.com offers the Kingston 8GB Class 4 microSDHC Secure Digital High-Capacity Card
with adapter, model no. SDC4/8GB, for $4.99
with free shipping
. That's $0.62/GB, the lowest total price we could find by $3, and the best shipped price we've ever seen for a Kingston 8GB microSDHC card. (For further comparison, we saw it with pickup for a buck less in March.) It includes a full-size secure digital adapter.
Don't need the adapter? Adorama has the card alone for $4.95 with free shipping.