Can a html button have php attributes?

I would use HEREDOC though

<?php
$id = 2;
$item_name = "cheese";
$item_price = 3.00;
$item_weight = 20;
$item_description = "Chedder Cheese";

echo <<< BUTTON
<button
    class="add-item"
    data-item-id="{$id}"
    data-item-name="{$item_name}"
    data-item-price="{$item_price}"
    data-item-weight="{$item_weight}"
    data-item-url="http://mysite.com/products/bacon"
    data-item-description="{$item_description}">
    Buy bacon
</button>
BUTTON;

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Awesome, that worked! :)

Sorry, Julian. Only got your response after accepting Marco's. Why would you recommend HEREDOC ?

Why would you recommend HEREDOC ?

PHP provides for three type of string output
Single quotes - everything inside the quotes is taken literally - there is no substitution of variable names. Single quotes must be escaped (\') double quotes can be used as is
Example

$name = "Julian";
$mystring = 'My name is "{$name}" and my neighbour\'s name is Fred';

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Will output

My name is "{$name}" and my neighbour's name is Fred

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Note the escape '\' is not in the output

Double Quotes - any variables in the string will be replaced with their values, single quotes can be used as is double quotes must be escaped (\")
Example

$name = "Julian";
$mystring = "My name is \"{$name}\" and my neighbour's name is Fred";

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Will output

My name is "Julian" and my neighbour's name is Fred

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HEREDOC is the best of both worlds
You can include both single and double quotes in the string without escaping them and you can include variable names. For situations (like yours) where you want to output a block of text with double quote (around the class names) and variables in the string it makes for a much neater ordering of your code.
Example

$name = "Julian";
$mystring = <<< ARBITARYTAG
My name is "{$name}" and my neighbour's name is Fred
ARBITARYTAG;

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You can read more about it here

Helpful, thank you!