I haven't seen any mention of the following domain registration sites:

ipower.com will register .com, .biz, .info, .net, .org, .us for US$5.50/year. This is charge to register and park domain until you find your own web hosting. Alternatively, domain registration is free if you sign up for 1 or more years of web hosting. (Or registration is US$20 with web hosting packages of less than one year --- go figure.)

In Canada, lowcostdomains.ca registers .ca domains for CDN$17.45 per year. This is a self serve registration service. (Can't go much less than this since the .ca regulatory body www.CIRA.ca charges registration companies CDN$15 per year.)