The crowdfunded Parallella-16 starter kit from adapteva seems to be the lowest-cost xilinx zynq starter kit at the same time. For USD 99 one gets a XC7Z010 board with 1GB DRAM, GB Ethernet, Flash, USB, and the 16-core epiphany processor.
But of course, one could use the FPGA only.
Andreas
(I pre-ordered mine last week, I am not associated with the project or with Adapteva).