I've been researching this a little.

Google Checkout and Paypal have exactly the same terms:

http://checkout.google.com/sell/ (click on "Costs and fees")

https://merchant.paypal.com/us/cgi-bin/?cmd=_render-content&...

Monthly Sales Through Google Checkout Fees Per Transaction

Less than $3,000 2.9% + $0.30

$3,000 - $9,999.99 2.5% + $0.30

$10,000 - $99,999.99 2.2% + $0.30

$100,000 or more 1.9% + $0.30

Old articles say Google Checkout has different pricing, so it must have changed.

Paypal makes you call for >=$100K.

Paypal also has a micropayments program which is 5% + 5c. If you do the math, for <$3K in sales, that's cheaper if a purchase is <= $11.90. Weird cutoff, but there you have it.

Paypal also has more payment options (you can link a bank account) and is available for international payments:

http://inventorspot.com/articles/zyngas_social_media_games_g...

I'm a Google fanboy, but Paypal looks to have the edge.

Here's an in-depth comparison of Paypal, Google, and a couple of smaller services:

http://foliovision.com/2010/01/21/paypal-google-checkout-dig...

Note: Lots of crabby blog posts when Paypal arbitrarily shuts down their accounts.

Anyone have practical experience?

As far as my understanding is, they both require you to go to their website, right? (Unless you pay monthly fee for paypal). I wonder if there is a solution which lets you accept payment on your own website with no redirect to any other site and only charges per transaction.

I forget the name, but Paypal has a system where they will handle transparent CC transactions (ie, user enters CC into your form and you submit to Paypal). The catch is you must also offer Paypal as an alternative to manual form entry. I found it through the Paypal developer resources... check there.

One big difference between PayPal and Google Checkout has to do with your users signing up for an account on their system. For Google Checkout, your users will also need to have a Google Checkout id before they can complete a payment. On PayPal Website Payments Standard (and I believe Pro as well) they can pay by credit card without being forced to create a PayPal account or log in to PayPal itself.

This is important because if you are targeting B2B sales then most wont be able to / wont want to create a google account.

http://aws.amazon.com/fps/pricing/

I know nothing about it other than that it exists and having briefly scanned 2 pages, here's a copy of one:

"Amazon FPS Pricing

There is no minimum fee and no start-up charges to use Amazon FPS. In addition, you can use the Amazon FPS Sandbox for free. Fees are assessed on a per-transaction basis and vary depending on the payment method used and the transaction amount:

    1.5% + $0.01 for Amazon Payments balance transfers.
    2.0% + $0.05 for bank account debits.
    2.9% + $0.30 for credit card for transactions above $10 and 5%+$0.05 for credit card for transactions below $10.

    Different fees apply for transaction amounts less than $0.05. Learn more about micro-transaction pricing and how you can qualify for volume discounts.

Note: This fee schedule is for payments by US customers only. For an additional charge of 1% of the transaction amount, non-US customers can make payments using credit cards (but not using Amazon Payments balance transfers or bank accounts at this time)."

With the little work I've done with Amazon Flexible Payments, I had to redirect to Amazon as well.

Although not free, cheddar getter will probably be cheaper than brain tree.

There are also some paypal functions that even though they take users to the paypal website, you can send them to a php?get= page where you can store subscription values in your database. I did this for a project I was bootstrapping a while ago.