Start, of course, by knowing the product - look in MSC, Isacor and the many other brands of cutting tools - many have on-line catalogs.
A one-inch diameter spade drill about a foot long will run a hundred bucks or so depending on brand and source. I got mine for less than 25 on ebay - new condition. The bits - I don't remember new costs - but I paid several dollars apiece for them.
Look at ebay prices. THEN WAIT! Watch for at least a month - you'll see them come and go in cycles - and with patience you'll get one for less than the shipping costs.