it depends on what kind of volume you want to make.
if you make small volume (1mL per run) the mini extruder from avanti is really good and all the spare pieces are available from Sigma-Aldrich which is usally fast on delevery.
if you are make bigger volume a barrel-extruder (pressure extruder) is a good idea.
i am using both the mini-extruder from avanti and the liposofast from Avestin (5-50 mL)
You can also look at getting a NanoAssemblr which does the same thing. Really depends on what you are trying to encapsulate and what volumes you are planning on working with.
I am having few addresses of liposome extruder providers. Please see if it is of help to you. May be you can ask for a quick quote with product specification.
T&T Scientific's extruders provide the fastest, cleanest and easiest way to prepare Liposome. They are single use which eliminates any risk of batch to batch contamination, and there is no need to spend 30+ minutes with cleaning and assembly.
T&T's NanoSizers are the most advanced extrusion technology available, and anyone can easily Order Free Samples and test them out. www.ttscientific.com/free-samples
Plus another benefit of NanoSizer is that when it comes time to scale up, there are there is the NanoSizer AUTO series for completely automated extrusion of anywhere from 10 mL to hundreds of liters. These devices significantly improve the repeatability and consistency of results by every time controlling the extrusion flow rate, number of extrusion passes and, the extrusion temperature.