If Statement With 4 Diffent Answers

This is my current formula that im using in cell U6

=IF(L6>=500,"Sept 8 2009","Sept 1 2009")

it works fine with just 2 answer cuz if its not one answer is another

=IF(AND($B$2>=0,$B$2>=500),"Sept 8 2009","Sept 1 2009")
found this one online but it got frustrating...i change the values to mine

so what im looking for is a if formula or similar to the following

if L6 is between 0-500 i want U6 to say Sept 1 2009
if L6 is between 501-750 i want U6 to say Sept 8 2009
if L6 is between 751-999 i want U6 to say Sept 15 2009
if L6 is between 1000-1200 i want U6 to say Sept 22 2009

i try both if formulas (stated above) both but both return one or more results...i just want one

so....Example

L6 U6
***(decimal included)
0.00 than i would get the result Sept 1 2009
253.52 than i would get the result Sept 1 2009
647.36 than i would get the result Sept 8 2009
750.01 than i would get the result Sept 15 2009
1100.00 than i would get the result Sept 22 2009

if above 1200 i would get the result sorry your amount owed is to high

formulas are preferred *but will work with macros and other options

*if using macros or vba or what have you please explain how it will work