Once the 250R is at the same level of repair as the new model (new bearings, seals, etc) it will be cheaper to maintain. Crack open a service manual for both engines and see which one you would rather deal with. Assume each part costs $5, then count up the parts and do the math. 4 strokes are much more expensive, but easier to ride. If you would rather build up your skill level, and spend less on parts, get the 250R.
1995 Titled Laeger Narrow Pro-Trax w/ 1991 CR5000 Linkage / All Stainless Hardware / Custom Axis Shocks / LSR Axle / Baldwin Anti-Fade / 265CC Mildly Ported National / Port Matched V-Force3 Reed Cage / 39mm PWK / No-Toil Air Filter / Custom Filter Bracket / ESR CR250 Ignition / Sparks MX Pipe / ESR Silencer / IMS 4G Tank Line-X'd / AC Bumper, Grab Bar, Pro-Peg Nerfs, Skidplate / Tag Metals Clamp / T2 Cannondale Bend Bars (Sandblasted) / TRX450R Front Brake Master / ODI Lock On Grips / 300EX Throttle