In general, French cars are little different from their German counterparts in real terms when it comes to reliability. It's just they had some blips a few decades ago which people still cling on to. Also, VW and co. have done a good job of upping their perceived quality when in truth VW has some of the worst mechanical reliability of modern manufacturers. I've worked in a VW franchise - they're not as bulletproof as people would have you think (in before people come in chiming they've never had a problem with their VW despite representing about 0.00001% of VW owners in the UK).
As for the 307, I will give you that it's unreliable by modern standards. It's the one car I would encourage people to steer away from. There are some good suggestions above. Clios are peanuts to run. If the mileage your brother does warrants a diesel then the 1.5dci might suit him. It costs peanuts to run, it's sturdy and genuinely good on fuel - look up cliodci.net, people getting 60+ mpg easily on the Mk1 and Mk2s. I currently have the Mk3 1.5dCi (106bhp), 9y/o and 100k on the clock. I'd expect £1.5k on a good day for it so the lower spec ones with 65 or 86bhp might fall into your price range. Surprisingly spacious for a 'small' car.