Transformer/Cap/Heatsink questions

I am getting a BOM ready for 4 amplifiers I am building. They are going to be used to drive 6.8" bass drivers - nothing else.

I'd like to ask a few questions on the following two transformers:

http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2238881
http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2238235

Do you think they are worth the money that is being asked?
Is it worth the extra R80 for the encapsulated version?
What would be the benefit of using an encapsulated version?
Do you have any suggestion for alternative sources? The ideal transformer I am looking for is 40-0-40V, 200-300VA, WITH NO HUM! The RS price for such is crazy!

Onto caps...

I need 4700uF/63V caps for the power supply. Will these do?

http://shop.rabtron.co.za/catalog/advanced_search_result.php?search_in_description=1&keywords=ER4700-63&x=0&y=0

Or does one need something like this: http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=1802087 or
http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3819087 or even http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5437019? 

Lastly, where is the best place to buy heatsinks? I need 0.6 deg/W.

I found this: http://za.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=490-7056&x=0&y=0. I could cut it in half to get to what I need.

Same question as before, is this a good price (if there is such a thing at RS...) or can I do better? Where?

Thanks a mil.