Watson,
Don't know if this will show up for non-business accounts or not but try...
Log into PayPal... choose Merchant Tools... In the Key Features links menu in the "PayPal Website Payments Standard" block choose "Donations"... At the bottom of the page turn off the option of having your button encrypted.., Choose your options and then click "Create Button Now"... You'll be shown two pieces of code, the first is an HTML form to insert into your HTML pages but the second one is a one-line URL meant for email links. You want the second one.

That will give you your URL link to use. If you want to use one of the stock PP buttons then on the prior page click on "Use A Different Button" to see the stock images. You now have a URL link and an IMG link. Just use a standard BB code IMG link inside of a standard URL link and you're good to go.
For example:
PHP Code:
[url=https://www.paypal.com/cgi-bin/webscr?cmd=_xclick&business=paypal%40cinvin%2ecom&no_shipping=0&no_note=1&tax=0¤cy_code=USD&bn=PP%2dDonationsBF&charset=UTF%2d8][img]https://vborg.vbsupport.ru/external/2010/02/12.gif[/img][/url]
Will produce.....
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