The price of first year can be estimated starting with a price of £25,800 for general tuition, then there's...

• three sets of plain robes, £300
• one plain pointed hat, £20
• one pair of protective gloves, £76
• one winter cloak (black, silver fastenings), £51
• one wand, £100
• one cauldron (pewter, standard size 2), £23
• one set of glass or crystal phials, £8
• one telescope, £108
• one set of brass scales, £8
• seven text books, £322

The total cost for the first year at Hogwarts comes out to £26,816 or $43,720 (as of 01 Aug 2011), not considering the cost of pets, scarves, uniforms, ink, parchment, and other incidentals that every student invariably faces. Nor does this analysis account for the premium paid for magical items.

for more info see centives blog.