Unless you can get generous trade discounts elsewhere, I would recommend RKM
Heating Controls at http://www.rkm-heating-controls.co.uk/index.html
I bought my (non RF) version from them - and they were cheaper than places
like PlumbCenter - even after paying postage. Be aware that you'll have to
send a cheque because they're not geared up to deal with credit cards.
RKM Heating Controls are doing them for UKP68.29 +VAT, or UKP71 + VAT for
the Optimum Start version. Their phone number (in case you can't access
their web site, as someone has suggested) is (01954) 261855
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