I don't think that anyone makes a kit.
JD (General Guitar Gadgets) supplies boards for RG's Neovibe project which is a replica of the Univibehttp://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=121&Itemid=26
All the information you need is available at the link above as it links to the project files at RG's Geofex site.
Also search on here as there is a lot of information about modification such as correcting for signal loss and possible modification using a LDR to replace the dual reverse 100KA pot used in the original.
I am just about to build my second one, I bought PCB's from JD for both projects. The new boards are excellent, worth buying to save yourself the trouble of making your own board. JD is very quick getting things sent out.
The neovibe uses a bulb and four photo cells (LDR's) not the Vactol type Led/LDR combination. Suitable photo cells (specification 16-33 on and 500k off resistance) and bulbs can be obtained from either Small Bear (America) or Banzai (Germany). Both ship around the world.
Suitable transistors 2N2908 or 2N5088 can be obtained from either store.
Or you could possibly use the 2N5089's that Aron sells in the DIY stompbox store here?
Hopefully this gives you enough information to get started.