we booked thru priceline last time and got a great deal on a three star hotel, but it was a little further away from the park.
for someone on a budget, i can highly reccomend the super 8 on disneyland drive, not katella. it's clean, the rooms are okay and the beds are really comfy. the only gripe we have with this hotel is the lack of parking close to the rooms, but all in all we really can't complain. it's usually about $68 a night booked thru expedia or orbitz.
you can buy tickets in advance, but there's no real point because you won't have to wait more than half an hour max at the ticket booth. you probably won't get a discount on the tickets, but if you get a good enough deal on the hotel then it about evens out.
i guess the best money-saving tip would be: don't drive/park in the parking garages. if you stay at a hotel that's close enough, then you can walk to the park. parking is $11 per day, and that can really add up.
also, for the two of you, plan to spend about $$70 on meals, snacks, and drinks a day minimum. if you want to eat someplace nicer like carnation cafe (breakfast and lunch only, on main st. w/ reservation), blue bayou (reserve a couple of days in advance, very $$$, but worth it at least once) or one of the other "sit down" type restaurants, it'll be a lot more. last time we ate at blue bayou we spent $110 w/ tip for just the two of us. food will get you, but if you don't eat breakfast or get coffee first thing in the park you'll save a little more.