It very depends on what kind of beer you prefer. Since I would recommend "Bauskas Special" or "Bauskas Lite", it's about 1 EUR per 0,5 l bottle in shops.
In restaurants (like "Lido") the 0,5 l mug of beer is about 2-3 EUR.
You may check
Palete Restaurant food prices, they are approx. the same in all restaurants. If you will eat in Lido, it could cost about 5-10 EUR per dinner, depends on what dishes you choose.
I mentioned all that incl. hotel information in
Hotel Reval Latvia thread.
There are also many other hotels available, it would be good to know the price you could allow, or what do you call "descent", before giving any further advices.
Where not to go in Riga - you may check my answers in
Getting to Riga thread.