Extending a small fragment of DNA
If what you trying to get is 1kbp of repetitive 150bp sequences, then synthesis as a large chunk might be better idea. It costs ~150-300$ but will potentially save tons of time. (see gBlock from IDT in US)

PCR and ligation with repetitive sequences is pain the butt. It might be true that you save money, but time and frustration could be more expensive.