I will second what is mention by others. The 401 is well worth money spend on a service, but you can often get very far with a thorough DIY clean up and maintanance. I would start by unscrewing needle plate, take out the bobbin case, clean under there, even take of the needle clamp and scrape out any dirt and grime out of every nook and cranny. I've had two machines slightly thrown out of timing because the space for the needle shank was packed full of grime. With a tooth pick I have poked out surpising amounts of grime from seemingly clean bobbin case and race on 201s. Use a reasonably fresh oil (less than 10 years old, if it has chanced color from clear to more amber it often turns sticky), even try fancy teflon on oil for an extra smooth turning mechansim. Detect all oil points, apply oil, turn the machine, and reapply; move all knobs and levers, test sew, and repeat it all the next few days. Pay extra attention to parts involving cams, stitch selector, make sure they move freely, click properly into place etc. Pick the top tensiner appart and clean the parts. The service manual for the 401 is available, and there's several helpful blongs and youtube videos on this model regarding timing and tuneup.
Any machine will eventually need a full service, but an extra thorough (DIY) cleaning and polishing can be a must once a year or so. All the settings and stitch patterns should work well on a 401, and it should run depedably and trouble free when sorted out. By going through the machine from one end to another, thoroughly cleaning up and tending to it carefully you can often detect the smaller issues causing the trouble. You have to invest some time and effort on the machine it self to save some money, but I guess it will be about half the cost to sort out the 401, compared to what you have estimated for your Bernina.
That said, my old Bernina 730 has very nice, even, satin stitches compared to the vintage Singers I've used. When money allows it spend some time and money on your Bernina too. A back up machine is a must; and at times I have a second machine threaded up and adjusted for specific purposes. Berninas have a few plastic gears but they are tough machines that stand up to any job you throw at them. With basic maintanance they tend run trouble free for years and years. I have had my two Berninas in for service a couple of times, but not nearly as often as a professional would recommend (which I think is once a year or so).