The 701HDV and 501HDV are very popular fluid heads for Manfrotto and currently Manfrotto is accepting Mail in rebates dropping the price down a bit. You can find the list of all Mail-In Rebates for the 701HDV & 501HDV fluid heads bundled with Tripods (click here).
Manfrotto 701HDV and Tripod Bundles with Rebates
If you're just looking for a deal on the 701HDV fluid head alone without Mail-In rebates, Amazon ships Prime and is just $7 dollars over the rebate price.
701HDV Fluid Head Only
Unfortunately, no rebates apply for the popular 561BHDV Fluid Head Monopod. Many people have been asking about this one that has sold out on both Amazon and B&HPhotoVideo.com. The only place to find a few are through one seller on eBay and luckily the prices weren't inflated.
561BHDV Professional Fluid Head Monopod