Electroporators for bacterial transformation

[PHILLIPSA at LARS.AFRC.AC.UK]

I'm considering buying an electroporator for routine transformation
of E.coli (XL1blue, DH5alpha etc) with plasmids and plasmid
ligations, to try to increase the number of transformants from
"difficult" cloning experiments. I need to know:
1. Do these machines really produce the advertised yield per ug (eg.
   1010) ie. are they worth having?
2. How easy are they to use/optimise?
3. Who sells the best (or, more importantly, best value) electroporator?

Is there anybody out there who can help me?

Thanks - Andy Phillips (EARN: PHILLIPSA at LARS.AFRC.AC.UK)
         AFRC-IACR Long Ashton Research Station
         Bristol BS18 9AF, UK