You want reagent grade, 70% concentrated Nitric Acid:

http://www.labdepotinc.com/chemical_details~pid~N1075.aspx

And either methyl alcohol (methanol) or ethyl alcohol (ethanol) to dilute it in:

http://www.labdepotinc.com/chemical_details~pid~M1240.aspx

http://www.labdepotinc.com/chemical_details~pid~E1029.aspx

As said previously, ALWAYS pour acid into the methanol/ethanol. NEVER do the reverse, as it will result in serious injury or blindness. Use rubber gloves and full face shield when mixing. To make 100 ml of 3% nital solution, measure 97 ml of methanol into a measuring beaker and pour into a plastic acid-resistant lab bottle. Then measure 3 ml of nitric acid into a plastic pipette or separate smaller measuring beaker that is dry (no drops of water or methanol remaining inside) and pour into the plastic bottle containing the methanol. The solution will get warm to the touch for a few minutes, but that is normal.

I can't say enough, ALWAYS mix acid into the solvent (methanol, ethanol, distilled water) to prevent serious injury.