Just got the reentry permit done at don mueang. If we prepared the TM8 form before hand, the fee would be 1000 baht instead of 1200. So basically its the same price if we done it at cheang watthana or any local immigration office.
TLDR : Answer Summary
The reentry permit fee at Don Mueang is 1200 baht, but if the TM8 form is prepared in advance, the fee reduces to 1000 baht. This means that the cost is the same when processed at other locations like Chaeng Watthana or any local immigration office.