I've just ordered the
Lassen DR+GPS at £50 + p&p and the
Epson XV-8100CB gyro at $50 + p&p. (notice currency) The gyro is listed in list of compatible devices, so I do not expect any surprices there.
The Lassen DR+GPS kit was too expensive for me at £500. But "Diamond Point" is kind enough to enclude some electronics in their documentation that will save me quite some time. If I had enough money not to care, I would buy the kit.
Thanks for all help so far.
I will post result when done, which will probably be in 2 months or so.