Your 'cheapest' option is to use a simple RAID Controller ~
http://www.newegg.com/Product/Product.aspx?Item=N82E16816132014
Define 'your' meaning of "esata raid array"?
How many external HDDs?
What MOBO do you have currently?
What exact "decent AMD2+" CPU is it?
BTW - I typically don't ever push Gigabyte, but I do know they have crazy SATA support.
Example:
GA-890FXA-UD5 (rev. 2.1) http://www.gigabyte.us/products/product-page.aspx?pid=3519#sp
CPU Support -
http://www.gigabyte.us/support-downloads/cpu-support-popup.aspx?pid=3519
South Bridge:
6 x SATA 6Gb/s connectors supporting up to 6 SATA 6Gb/s devices
Support for SATA RAID 0, RAID 1, RAID5, RAID 10 and JBOD
* SATA3 RAID 0 4x and SATA3 2x performance are maximum theoretical values. Actual performance may vary by system configuration.
GIGABYTE SATA2 Chip:
1 x IDE connector supporting ATA-133/100/66/33 and up to 2 IDE devices
2 x SATA 3Gb/s connectors supporting up to 2 SATA 3Gb/s devices
Support for SATA RAID 0, RAID 1, and JBOD
JMicron JMB362 chip:
2 x eSATA 3Gb/s connectors (eSATA/USB Comobo) on the back panel supporting up to 2 SATA 3Gb/s devices
Support for SATA RAID 0, RAID 1 and JBOD
ITE 8720 chip:
1 x floppy disk drive connector supporting up to 1 floppy disk drive
GA-870A-UD3 (rev. 2.1) http://www.gigabyte.us/products/product-page.aspx?pid=3517#sp
CPU Support -
http://www.gigabyte.us/support-downloads/cpu-support-popup.aspx?pid=3517
South Chipset:
6 x SATA 6Gb/s connectors supporting up to 6 SATA 6Gb/s devices
Support for SATA RAID 0, RAID 1, RAID5, RAID 10, and JBOD
* SATA3 RAID 0 4x and SATA3 2x performance are maximum theoretical values. Actual performance may vary by system configuration.
GIGABYTE SATA2 chip:
1 x IDE connector supporting ATA-133/100/66/33 and up to 2 IDE devices
2 x SATA 3Gb/s connectors supporting up to 2 SATA 3Gb/s devices
Support for SATA RAID 0 and RAID 1 and JBOD
JMicron JMB362 chip:
2 x eSATA 3Gb/s connectors on the back panel supporting up to 2 SATA 3Gb/s devices
Support for SATA RAID 0, RAID 1, and JBOD
iTE IT8720 chip:
1 x floppy disk drive connector supporting up to 1 floppy disk drive
Good Luck!