Good Juniper Material?

Hi,
I am new to bonsai and found a local nursery owner who has a large number of old variegated junipers. They have beautiful trunks and nice curves, but they were crowded in together and have long spindly branches. The issue is that I don't know how hard it will be to get back budding. How long would it take and is it possible to get these full enough to cut them back to a nice size? I have purchased two of them. Are these good bonsai material and should I buy more? Any suggestions on increasing vigor and causing back budding would be greatly appreciated.

Also, are variegated Junipers desirable and how much would these trees be worth in their current state?

First Tree:






Second Tree:

Personally I do not like verigated Bonsai they tend to look poorly most of the time. Not sure what Juniper this is but it has been kept in the shade far too much hence all the moss on the branches and trunks. I see some back budding so guess it will given sun, and feed. The other problem is hard juvenile foliage , you will always have a battle to get rid of this . Good luck

Don't buy any more.  These will be a long term project.  Lots of sun, plenty of feeding once they are in active growth, and make sure the top growth does not shade out the inner branches.  

I have one I have spent years nurturing, and I forget why I bothered:

June 2014:

IMAG0398 by BrendanR2012, on Flickr



September 2017:

20170923_184545 by BrendanR2012, on Flickr