Hi there: as far as I know all small motorcycles (below, say 500cc) only come with rear chain drives ... even BMW offer only chain on their F650GS models, I have one; and can tell you maintenance to it is only required every 1000km (600miles) and that by way of a spray can. If you do lots of off-road riding this distance/maintenance would obviously be reduced/more necessary. You don't say if you considering new or old, but most scooters today are of the automatic (CVT) type, I recently rode a Honda Integra (scoot lookalike but big wheels, ie 17-inch) 700cc and thoroughly enjoyed same. Superb brakes (linked) and even ABS ... fuel consumption better than 3.9 litres per 100km (not sure what that is in your money, I live in South Africa. Your concerns over chain drive are not to be feared ... sprockets/chains at worst only need to be replaced at 16000km (10 000 miles) ... Adjustment usually a doddle but does need to be done properly ... Enjoy!