There are three FDA approved products to treat glabellar lines: Botox, Dysport and Xeomin. Botox (onabotulinumtoxinA) is distributed by Allergan and has the longest track record. Dysport (abotulinumtoxinA) is available through Medicis, and the most recently released neuromodulator on the market, Xeomin (incobotulinumtoxin A), is made by Merz.
There are several other products which do not have FDA approval, but are largely utilized in other countries. Many of these are available for purchase on the Internet. Neuronox is used primarily in South America. Botulax and Chinatox are similar products used as neuromodulators (wrinkle relaxants). Any of these products could be used to substitute the FDA approved ones which you are familiar with. Howver, little is known in terms of efficiency and safety. These products tend to be offered at lower prices.
Take caution when you shop around for such treatments as there are many unbranded products available on the Internet.
When one of these products was tested by Allergan, it was found to contain 250 times the dose of the same size vial of onabotulintoxin A, found in Botox. Keep in mind that in many countries, there are no regulatory organizations or quality control.
Just be careful!