Credit Card (eftpos) reader(Portable) research

General information for the business: I am an artist who sells work at 4-5 Exhibitions per year.
Industry: Art and Design
Geographical areas: Perth, Western Australia
Data to include: I need to get a comparison chart made that compares information for mobile credit card readers. This chart should compare: Smartphone readers: Square Register, Paypal Here, Payleven, IZettle, Swiff Pay Anywhere, Intuit Gopayment, Phone Swipe, and Verifone Sail. This chart should also include; Portable Eftpos machines, available for rental from major Australian banks such as ANZ, CBA, Bankwest, etc.
Extra notes: Fields in the chart should be: Name, address and phone details of Supplier, Name of unit, Cost to buy unit (if offered), Term of contract (1 month to ?), Monthly fee, Exit fees, Cost per transaction (visa, mastercard, Amex, eftpos), Keyed-in Charge, Swipe Charge, GPRS (yes or no), WiFi (yes or no), Battery or Plugin, Battery Life in hours, Are they Android or Apple?, Available in Australia?, Or can they be purchase elsewhere in the world but still be able to be used in Australia?
Here is something to help you get started.
http://www.hongkiat.com/blog/smartphones-into-creditcard-readers/

As an artist who only does a few shows a year I need something flexible, cheap and versatile. If it is a unit that I can use for a month or two and then return without paying exit fees that would be desirable. Any advice or thoughts on this research would be appreciated too. Thank you in advance