Thank You For Thank Retail Store For Value
Dear {Manager},
Thank you for agreeing to apply a discount on the {item} I purchased {earlier today/yesterday}. I had been in need of one for quite some time now, but I have had to hold off due to financial restraints. I don't really mind {the scratches/that it's a floor model}, what matters is that it still works.
Thank you for your kind understanding.
Sincerely,
{Your Name}