Prague offers a variety of accommodation choices according to your preferences. Budget options offering a good balance between comfort and price are for example the following:
****Hotel U Staré paní http://www.hotelustarepani.cz (available also at booking.com), in the walking distance (17 min.) from the conference venue and near the metro.
***Aparthotel Angel http://www.aparthotelangel.com (available also at booking.com), right at the metro line B which connects you with the conference venue.