Cheap capiliary style matting?

Anyone know of a cheap solution for a fairly reasonable quantity of capillary matting? As some of my trays are not covered by plastic lids, I am struggling to retain water, and in turn nothing will germinate if there isn't any moisture. I was wondering about something like sponge carpet underlay, but I am not sure if it is absorbent?

Basically, I am looking for something to sit the trays on that would soak up moisture and then in turn hopefully assist in keeping the trays a bit moist. Some of those trays are half-size, 12-cell trays.

If I could line a shelf with something in one strip, it would be handy?

 

Temporary fix is all I need really @NigelJ - a matter of weeks really and the plants should be out doing their thing in the garden. I must admit, I never thought of newspaper - thank you

 

Nah, sadly not @mowgley - that or carpet underlay was among the first things to mind.

 

Well, I partially resolved the issue this evening - Sainsburys were selling nice sturdy gravel trays for £1 each, so it would have been rude not to...................



























Clear them of their entire stock! 19 purchased and pressed into service - they will hold a wee bit of water under the trays to keep them going.