how are prices for decent lunch or dinner in Madrid, nothing fancy. I´m going there in mid october?

Answer 1

You have plenty of choices...
Lots of restaurants have luncheon menus "menu del día" for a reasonamble price, best range between 8 and 10 euros.
Then, if you prefer snacking, you have what the spanish call "Tapeo"... A tapa is a snack sized portion of any dish, and bars and restaurants usually have a full menu of various tapas... The tapa should not cost you more than 1 or 1,50 euros each, and with some good ones, 4 should be enough to fill your tummy!
They are usually in full view on the top of the bar in a refrigerated glass case, so you can choose just by pointing at the ones that pick your fancy!
For dinner you have many excellent restaurants all across Madrid... A fair dinner menu should cost you about 12 to 15 euros (wine not included).
Try a local dish... "Cocido Madrileño", it's a winter dish, and has veggies, chickpeas, meat, and chorizo sausage...really filling and very tasty. Great for a chilly or rainy october day!

Answer 2

For lunch many restaurants have the "menu del dia" (2 dishes, dessert and one drink) who is a good option. Less than 8 euros is not advisable 8-10 euros are the most common prices and menus with a price higher uses to have a very good quality. For dinner there are a few menus offered and usually in the upper range of prices. Cost for a lunch od dinner out of the "menu del dia" is about 25-35 euros per person but in good restaurants could arrive to 50-60 euros. The prices are shown in most cases at the street