If you can spend $800, here is an enzyme assay kit for vitamin B6:

http://www.acdiagnostics.com/B6%20Assay_3-fold%20brochure-3.pdf

Here is an HPLC assay kit for only $490:

http://www.eaglebio.com/vitamin-b6-whole-blood-hplc-assay-kit/

Thanks Sir ADam i was actually searching for some cheap method and easy it can b indirect !

There are some microbiological methods in the literature (and also some expensive commercial kits based on them). Once you get the appropriate microorganisms (try the ATCC) whose growth is highly dependent on exogenous vitamin b6, these methods should be inexpensive to perform, since they just measure the effect of the vitamin on growth. You would need to calibrate the assay with pure vitamin b6.

http://link.springer.com/chapter/10.1007%2F978-1-4684-9901-8_2#page-1

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1258433/