Don't even think about it. If you want to dune, get the R. I have 2 of them, ride them everywhere, they're dependable, have lots of power that can cheaply be upgraded, look bitchen, ride nice, fix them easily, etc. I won't ever get rid of mine.
You can find them. It requires patience and persistence, but good ones for a good price are out there.

 

I have an 87 250r and my friend has a 1999 400EX. They are both close enough to each other that it all comes down to the rider. My R is a little faster in a drag race and slides easier but his 400 hooks up better. Like someone said earlier, they don't seem that fast because of the smooth power delivery but they are. I honestly really like his 400 and would have boughten one if I hadn't found my R first. I do think that the R is alot easier and cheaper to modify...but that is slowly changing as the aftermarket companies are starting to make tons of stuff for the 400 now.

Don't let reliability issues keep you from an R, they are very dependable and are super easy to rebuild if they do blow up. The bottom line is both quads are awesome - you would like either one of them - especially when compared to a Banshee.

 

2-strokes are less reliable. My friend also consistently has trouble with his blaster, but that is a Yamaha. The R either has stock parts that are 12 years old and are ready to break or has been heavily modded, raced, and therefor also ready to break. I have a 400 and love it. I can easily beet a blaster and since you are on a budget I would recomend a 400.

 

blasterryder: in your post you said you wanted the 400ex because of "no maintainance" Just what exactly do you call oil changes, oil filter changes, valve adjusting, timing chain tightening and air filter cleaning to name a few? sounds like maintainance to me. 2 strokes are no more maintainance than 4. They both need air filter duties, either tranny/cranckase oil needs changed, and 2 strokes need oil mixed w/ gas which takes 10 seconds. No valves, timing chain or camshaft to screw up on a 250r. As for piston/ring changes, take care of your engine (proper mix ratio and jetting) and you wont have to touch the top end for years to come, unless raced or abused.
If you can find a good 250r grab it because someday youll wish you had.

 

Thanks for the help guys 250r on the way just need to find a good one

 

I'm glad you saw the light and went with the R...you won't be disappointed.

As stated in the above post, many people have a preconceived notion that a 2-stroke requires much more maintenance than a 4-stroke. The above post covered this pretty well, but forgot to mention one thing. While the 2-stroke top end may wear out a year sooner than the 4-stroke, think of the cost and time involved to repair it. A 2-stroke top end can be disassembled, bored, and have a piston installed in a week or less. It will cost you around $150. A 4-stroke, on the other hand, will take you much longer to disassemble(valves, timing gears, cams, timing chain, more rings) and much more money to buy all the new parts.

As far as reliability is concerned:
If you are lazy and fail to perform routine maintenance on any machine, it will fail. Four years ago, my friend bought a '97 Blaster. I bought mine 3 months later. I broke mine in properly, maintained it perfectly, and rode it just has hard as he does. Needless to say, mine still runs strong....his is currently sitting in the shop. It tends to spend more time being repaired than it does running.