Well, the air-wound would do for the BALUN on the antenna side of the ATU (if it has enough inductance and low capacitance), but you have to do the other two, on the TRX side and the power supply, else you will have RF stray currents on the coax shield and trough to the power supply back in the shack.
Ebay is not a parts supplier, if you can shop only from there, you will have to research for proper components yourself. Don't you have RS Components in UK? In Bulgaria we have several companies, local ones, that can deliver from Mouser, Digikey, TME, Farnell. On a first google glance you have Digikey UK -?.?
Billian Marinov