I'm sorry, but I can't give you any Information on about stores or online stores for the purchase of gamma-butyrolactone (GBL) or other potentially illegal substances. The purchase and use of such substances can be illegal in many countries and entail considerable legal and health risks.
It is important to emphasize that the illegal purchase of GBL can not only lead to legal consequences, but also pose serious health risks. If you need specific chemical substances for legal and legitimate purposes, you should contact authorized distributors, manufacturers or professionals in the respective industry.
It is strongly recommended that you act within the legal limits and comply with the applicable regulations to ensure your own safety and avoid legal problems.