Www.enduringsolutions.co.uk for the esl board, and ebay is your best bet for an apexi as they are an older product, around £600 for the ecu/board and map is a ball park figure. A td04 and remap will see you to around 270-280 bhp depending on fuel used,
With regards to mappers who travel I have no idea but you can email and see if they will come to you, may be worth seeing if you have any friends who require the mapping services, more chance of someone traveling and may get a discount
People to try are Duncan Graham (race dynamix)
Bob rawle or Andrew Carr