I do understand what you are saying and what you desire to do. I am merely passing along the information.
Many apps have free or lite versions that give you basic functionality that let's you see the basics of what the app can do and they offer paid upgrades if you like what the app can do and how it performs for you. Having said that, unless the app provides that comfort zone option, there are no refunds for apps because they don't live up to your expectations.
Copied from the iTunes Store Terms and Conditions. The bold type below is for emphasis.
A. ITUNES STORE, MAC APP STORE, APP STORE, AND IBOOKS STORE TERMS OF SALE
B. ITUNES STORE TERMS AND CONDITIONS
C. MAC APP STORE, APP STORE AND IBOOKS STORE TERMS AND CONDITIONS
THE LEGAL AGREEMENTS SET OUT BELOW GOVERN YOUR USE OF THE ITUNES STORE, MAC APP STORE, APP STORE, AND IBOOKS STORE SERVICES ("SERVICES"). TO AGREE TO THESE TERMS, CLICK "AGREE." IF YOU DO NOT AGREE TO THESE TERMS, DO NOT CLICK "AGREE," AND DO NOT USE THE SERVICES.
A. ITUNES STORE, MAC APP STORE, APP STORE, AND IBOOKS STORE TERMS OF SALE
PAYMENTS, TAXES, AND REFUND POLICY
You agree that you will pay for all products you purchase through the Services, and that Apple may charge your payment method for any products purchased and for any additional amounts (including any taxes and late fees, as applicable) that may be accrued by or in connection with your Account. YOU ARE RESPONSIBLE FOR THE TIMELY PAYMENT OF ALL FEES AND FOR PROVIDING APPLE WITH A VALID PAYMENT METHOD FOR PAYMENT OF ALL FEES. For details of how purchases are billed please visit support.apple.com/kb/HT5582.
Your total price will include the price of the product plus any applicable sales tax; such sales tax is based on the bill-to address and the sales tax rate in effect at the time you download the product. We will charge tax only in states where digital goods are taxable.
All sales and rentals of products are final.
Prices for products offered via the Services may change at any time, and the Services do not provide price protection or refunds in the event of a price reduction or promotional offering.
If a product becomes unavailable following a transaction but prior to download, your sole remedy is a refund. If technical problems prevent or unreasonably delay delivery of your product, your exclusive and sole remedy is either replacement or refund of the price paid, as determined by Apple.
If you care to read the entire thing.
iTUNES STORE - TERMS AND CONDITIONS - Apple