If you don't have the ability to consistently collect information about your customers, consider the following user interface option, which, by the way, is already used by the World Wildlife Fund.
Instead of specifying specific amounts, the marketers left it up to the user to choose the amount they would like to donate to the Fund each month, but provided an example in brackets.
World Wildlife Fund
In another example, The Environmental Defense Fund asks lebanon phone number data visitors to choose an amount between $25 and $5,000. Although the automatically allocated value is $50 (which, by the way, may be the most common choice for most site visitors or may be due to the operation of a particular user's cookies), there is an implicit indication that the organizers expect a donation of at least $25.
The Environmental Defense Fund
Another way to explain the benefit of this solution is that $5,000 donations seem real to the average visitor (someone actually donates that amount, otherwise it wouldn't be included in the selection line), which makes $50 seem like a small amount. But the automatic selection kind of tells the user that the organizers are grateful for a donation of any size.
Notes
1. Horizontal radio button placement is less preferable. As you can see in the example above, the following problem arises: it is not entirely clear which amount a particular button refers to - the one after or the one before the button.
This flaw is even more noticeable in the mobile version of the site. To avoid such flaws, use a vertical layout for the radio buttons.
2. Try to make buttons larger.