Unknown price difference for xilinx fpga

I have been learning about fpga's for a month now, and stumbled across
the merec web site.

I am looking for a dev board with 20000-30000 LC's and two jumped out
at me.  The DS-KIT-4VLX25LC and DS-KIT-3SMB1500 both are in that range.
 One is a virtex 4 the other a spartan 3.  I cannot figure out why the
spartan board is twice the price of the virtex 4 board.  The spartan
has only 5k more lc's while the V4 has more Dsp/multiplier units and
>twice the block ram.  The boards seem comparable to each other in addon features...
I could see some difference due to the 5k LC's, but twice?

http://legacy.memec.com/devkits/americas.shtml
http://www.xilinx.com/products/tables/selector/index.htm

What am I missing?

One board is listed at $295, the other at $595.   It doesn't take many
additional parts and features to take a bite out of $300.

The Spartan 3 is in an FG676 package, the V4 in the F363 package.   In
general, the more IO's,  the more $$.  The  3S has two expansion slots
and on-board flash, and a speaker in addition to the  DDR mem, switches
and LCD that they have in common.

Board pricing from distributors is not totally dependent on the true
silicon cost.  They receive compensation from supplier marketing groups
 to promote new parts and features.  It is not only the FPGAs that are
being promoted but also the other components as well.

Pip

In order to program the V4 I would have to use the jtag cable?  Also
what is "serial data flash"?  an add on?

Thanks