$2.49/£1.99 .com domain (1 per new customer) at 123 reg (UK registrar)

[leternal]

There's an ongoing promotion for .com domains at https://www.123-reg.co.uk/domain-names/

$2.49/£1.99 .com domain (limit 1 per cutomer)

I don't have experience with this registrar, so tread carefully.

 

[TheHawking]

They are good and the promotion has been running for like one year now