I paid $329 for my Janome Magnolia 7330 back in 2009 & I really like it. I have a Singer TouchTronic that I used before the Janome. There are features that I like on my Singer & features that I like on my Janome. My Singer has a bobbin warning light that lets you know you are getting close to running out of bobbin thread & I dearly love that feature. My Janome has a needle down feature that is a fantastic feature. I also like the fact that it has a speed control so you can increase or decrease your speed depending on what you are sewing. I think the only thing I wish the Janome had was more decorative stitches. It doesn't even have the simple serpentine stitch.
I definitely agree that you should not let the sales person know how much you are willing to spend. They work off commission & will try to sell you something up to your limit. You may not need to spend that much depending on the features you want/need. Also, make sure you are close to the place where you bought it so you can go for lessons (if offered) & repair. Keep your old machine. When one machine is in the shop for repair/cleaning you will still have something to sew on.
Good luck & have fun in buying your machine. Don't feel pressured to buy the day you go look. The machine will still be there the next day.