Where can I get these? Can't find them on the lego site but don't know if I'm searching right. I'm looking for something like 4x30 ish long or 6 x 30 ish long

Do you actually mean base plates or just plates?  What is the advantage of base plates?  And if you are just using plates then you don't necessarily need really long ones, do you?

 

More info required, please!

I wanted a long piece so I could make a stand for my minifigures. Ideally I wanted one long piece but if I have to use smaller pieces I will

If it's just for a stand, then you may want to consider non-Lego (e.***. Megablocks or Kreo).  Probably cheaper, and means you can save Lego for actual building.

According to Bricklink, the longest plate is 6x24, and there is an 8x32 option for base plates.

 

http://www.bricklink.com/catalogItem.asp?P=4187

 

http://www.bricklink.com/catalogItem.asp?P=3026

It's too bad the Lego site does not sell 16x32 baseplates separately same as the 32x32 ones (unless I missed that product page).

According to Bricklink, the longest plate is 6x24, and there is an 8x32 option for base plates.

 

http://www.bricklink.com/catalogItem.asp?P=4187

 

http://www.bricklink.com/catalogItem.asp?P=3026

This is the sort of thing I'm after! When I type the codes into the lego pick a prick site I can't seem to find them so guess I'll have to go second hand. The search facility on the lego site doesn't seem to work that well

Yes it can be a normal plate

This is the sort of thing I'm after! When I type the codes into the lego pick a prick site I can't seem to find them so guess I'll have to go second hand. The search facility on the lego site doesn't seem to work that well

They don't sell everything on pick-a-brick, so it may be that they don't carry them 100% of the time.  I think it was the baseplate I linked that isn't made anymore, so you'd definitely have to bricklink that one.  The plate you could see what set it is in and call lego and have them check out if they have it in stock. 

Found them on lego site now thanks as normal plate is fine for what I want, thanks for the help

This is the sort of thing I'm after! When I type the codes into the lego pick a prick site I can't seem to find them so guess I'll have to go second hand. The search facility on the lego site doesn't seem to work that well

 

Lego stopped producing 16x32 so bricklink is your best bet for pretty much any size.  They sell 16x16 and 32x32 in stores and TRU.