So, after much gnashing of teeth i figured out how to get the PayPal "Buy Now" button to work correctly*. Here was my issue;
Using the PayPal "Merchant Services" "Buy Now Button", i was able to create the button, but when using the HTML functionality of SilverStripe, it just created the little table, but the button would not show up. There was nothing to click on, and hence no PayPal like functionality.
I'm not talking about the Ecommerce module, just pasting the provided HTML in the page and making it work. After moving thru the archives, and doing some reading, I got a feel for what the cause of the issue was. I wont bore you with that. Lets just get to what I did (in the end).
First, find your tinymce.template.js (mine was in the cms/javascript/ directory, I say that only because most of the posts don't tell you where to find the stinking files). Make a copy of it, just in case.
Open it with your favorite text editor and look for the following line;
valid_elements : "+a[id|rel|rev|dir|tabindex|accesskey|type|name|href|target|title|class],-strong/-b[class],-em/-i[class],-strike[class],-u[class],#p[id|dir|class|align],-ol[class],-ul[class],-li[class],br,img[id|dir|longdesc|usemap|class|src|border|alt=|title|width|height|align],-sub[class],-sup[class],-blockquote[dir|class],-table[border=0|cellspacing|cellpadding|width|height|class|align|summary|dir|id|style],-tr[id|dir|class|rowspan|width|height|align|valign|bgcolor|background|bordercolor|style],tbody[id|class|style],thead[id|class|style],tfoot[id|class|style],-td[id|dir|class|colspan|rowspan|width|height|align|valign|scope|style],-th[id|dir|class|colspan|rowspan|width|height|align|valign|scope|style],caption[id|dir|class],-div[id|dir|class|align],-span[class|align],-pre[class|align],address[class|align],-h1[id|dir|class|align],-h2[id|dir|class|align],-h3[id|dir|class|align],-h4[id|dir|class|align],-h5[id|dir|class|align],-h6[id|dir|class|align],hr[class],dd[id|class|title|dir],dl[id|class|title|dir],dt[id|class|title|dir]",
and replace it with the following;
valid_elements : "+a[id|rel|rev|dir|tabindex|accesskey|type|name|href|target|title|class],-strong/-b[class],-em/-i[class],-strike[class],-u[class],#p[id|dir|class|align],-ol[class],-ul[class],-li[class],br,img[id|dir|longdesc|usemap|class|src|border|alt=|title|width|height|align],-sub[class],-sup[class],-blockquote[dir|class],-table[border=0|cellspacing|cellpadding|width|height|class|align|summary|dir|id|style],-tr[id|dir|class|rowspan|width|height|align|valign|bgcolor|background|bordercolor|style],tbody[id|class|style],thead[id|class|style],tfoot[id|class|style],-td[id|dir|class|colspan|rowspan|width|height|align|valign|scope|style],-th[id|dir|class|colspan|rowspan|width|height|align|valign|scope|style],caption[id|dir|class],-div[id|dir|class|align],-span[class|align],-pre[class|align],address[class|align],-h1[id|dir|class|align],-h2[id|dir|class|align],-h3[id|dir|class|align],-h4[id|dir|class|align],-h5[id|dir|class|align],-h6[id|dir|class|align],hr[class],dd[id|class|title|dir],dl[id|class|title|dir],dt[id|class|title|dir],form[accept|accept-charset|action|class|dir<ltr?rtl|enctype|id|lang|method<get?post|name|onclick|ondblclick|onkeydown|onkeypress|onkeyup|onmousedown|onmousemove|onmouseout|onmouseover|onmouseup|onreset|onsubmit|style|title|target],input[accept|accesskey|align<bottom?left?middle?right?top|alt|checked<checked|class|dir<ltr?rtl|disabled<disabled|id|ismap<ismap|lang|maxlength|name|onblur|onclick|ondblclick|onfocus|onkeydown|onkeypress|onkeyup|onmousedown|onmousemove|onmouseout|onmouseover|onmouseup|onselect|readonly<readonly|size|src|style|tabindex|title|type<button?checkbox?file?hidden?image?password?radio?reset?submit?text|usemap|value]",
Save the file and open your admin console. (Some of the archive posts talk about adding *everything* XHTML but I was not 100% on that. So, I just added what I thought was needed.) With those changes made open your target page and select the HTML button up on the second row. Paste your code from PayPal in the HTML window.
This will be the code that starts
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
and ends with </form>
Be sure to select Update and then Save & Publish.
Your PayPal "Buy Now" button should now be visible and accessable on that page. I hope this works for you as well as it did for me.
*I claim no expertise with SilverStripe, PayPal, or anything larger than 12 oz glass container. Edited for clarity and spellin'