Indeed, there are ACh kits available to measure ACh indirectly (basically measuring the choline colormetrically or florometrically. You can easily find the suppliers. Be aware the stability of ACh in the sample. Good luck!
Do you need an in vivo technique for the measurement of acetylcholine? (I think, you may referred to microdialysis+HPLC) If so, than ACh can be measured in vivo with electrochemical techniques by using biosensors. I recommend you the papers below. Although these aren't the newest publications in this field and are not only about ACh, but you can start here, and follow the references.
Article Review of recent advances in analytical techniques for the d...
Chapter Carbon Fiber-based Microelectrodes and Microbiosensors