There is a large choice of hotels, bed and breakfast (residencial or pensão), apartments and hostels (dorms) in Lisbon.
Main hotels are searchable in booking.com and a useful list of budget hotels can be found here.
Apartments and Hostels are mostly recently renovated picturesque buildings in the city centre. They tend to be convivial.
Residenciais/Pensões are mostly old-fashioned cheap hotels. Some are a good budget choice, with reasonable quality at a third of the price of a hotel. Some may be a bit shabby, depending on location. A useful list can be found here.
Be aware that finding accommodation in Lisbon during Easter time might be difficult, thus booking in advance is advised. We have arranged for 25 rooms at VIP Executive Zurique Hotel (see map) dedicated to the meeting at the price of 60€ for single or 65€ for double occupancy, breakfast included. The hotel is located 45min walking distance to the conference venue or 18min by metro. In attachment we send you the hotel’s accommodation booking form in case you would like to choose this hotel. To guaranty this fare, you should book before the 28th of February.