If you want to purchase something that I make, contact me at my email: j6summers@gmail.com.
If it is something that I have on hand, I will send you a paypal request and once I get notice that you have paid, I will box up your order and take it to my local post office.
If you want something that requires some effort to put together, I will tell you that, give you a quote and a time estimate before sending the Paypal request. Be aware that the time estimate is just an estimate.
Sometimes I am willing to do some design / prototyping / development work for a customer. Sometimes I am not. It doesn't hurt to ask.
Be aware that I may not want to sell you something. A lot of the stuff we have made I don't really feel like producing for the market. Usually, this is because the software is not refined to where I want it, or I have perhaps lost the files. Sometimes I am just too busy. We are a one-person operation and I don't have the time or energy to do some of the things I want to.
Sometimes things are not in stock. I fund this out of my own pocket and don't keep large inventories of expensive parts. If you order something that requires a servo motor, I will order the motor from ServoCity.com and it will take some time to get here. If I run out of concave mirrors and need to have them ground to order, that process (and shipping from China) takes quite a while and the cost will not be what I paid in 2015.
I send things by USPS Express Mail or Express Mail International. A small box by Express Mail ships in the US for $12. A potentiostat will fit in a small box but a syringe pump will not. You can email asking me for dimensions. For costs to ship outside the US or different sizes, please see the USPS Price Calculator.
If you really don't like the USPS, I can ship by UPS. It is a bit of a drive for me and they keep funny hours but I can do it.