I've found that without a slicer, the best way to slice streaky bacon from a cured belly is by rolling it into a tube and wrapping it with cling flim then slicing.
It works pretty well, and as per all the previous posters, it's so easy to make and beats any of the shop bought stuff. You can knock up a really simple cure with some Sugar, salt and cure#1 then you can adjust the saltiness/sewwtness to suit your own pallate... If you've got the facility to cold smoke - even better !