Please help to recommend the hotels in Brussels. Thanks.

The first sentence of your post didn’t make sense to me, until I read your last. I’m afraid your budget is not realistic for a nice hotel in central Brussels. This is regardless of the time of year, not just for October.
I’m also not sure why you don’t know how much the price of Motel One Brussels is. As is the same with every other hotel, their room rates are mentioned on their website. Plug in your dates and you’ll see the rates for the various types of room they have.
Given your seemingly tight budget, you should realize that the countries and cities you plan to visit are not budget destinations. There are of course tips and tricks for the budget conscious visitor, but in general things aren’t cheap.

I’m also not sure why you don’t know how much the price of Motel One
Brussels is. As is the same with every other hotel, their room rates
are mentioned on their website. Plug in your dates and you’ll see the
rates for the various types of room they have.

Sorry for not being clear. What i meant earlier is, booking.com states that the twin bed is not available, hence you are not able to see the price of that twin bed and even all room types for the certain dates. Even all room types of Motel One Brussels are not available for these certain dates. That's all.

Hmm...i thought that during summer, the hotels offer the reduced rates. I try different months on booking.com and sure enough, in summer, there are cheaper rates offered by the hotels including Motel One Brussels.

I guess i have to increase my budget a bit. Thanks for telling me this. Nevertheless, can you recommend the cheaper hotels?

As you’ve found out already, room rates are very much date dependent. So without knowing when you want to stay in Brussels exactly, it’s difficult to give specific advice.
Also, there are no “secret” hotels. Most, if not all, hotels will be on Booking and the likes. In many cases though, you can get a cheaper rate by booking directly at the hotel. I myself use Booking to search for hotels and then book directly with the hotel.

I myself use Booking to search for hotels....

Same here. We can't provide accurate prices without dates - they're going to vary based on local events, conferences, etc - so exploring your options by your specific dates and desired price on that website (or others you might be using) will be your most efficient method. Include hostels as well as hotels as some of them offer private rooms.

We stayed at the NH Brussels Grand Place Arenberg for a night some years ago and it worked well for our purposes: short walk from Centrale station, the cathedral, Grand-Place, etc. Perfect? Maybe not for a longer stay, and booking.com shows Oct. rates well above your budget so.... I think you're going to have issues with such a low budget, thus looking at hostels.

https://www.hostelworld.com

One example? This one offers private rooms, is centrally located and rated very highly on both hostelworld and booking.com:

https://www.booking.com/hotel/be/latroupe-grand-place.html?label=latroupe-grand-place-GbmyJUjT0A6ra*P4icVW2QS589956689251%3Apl%3Ata%3Ap1%3Ap2%3Aac%3Aap%3Aneg%3Afi%3Atikwd-1514017483813%3Alp9019610%3Ali%3Adec%3Adm%3Appccp%3DUmFuZG9tSVYkc2RlIyh9YfNeh-lbHkPZ0F1ArkOgkMs&sid=19fd1d4aa4e50d53ee1dc84b7d91af30&gclid=EAIaIQobChMIrYvX8pPsjgMVs9HCBB1FKif1EAAYAiAAEgLQ6PD_BwE&aid=311088&ucfs=1&dest_id=-1955538&dest_type=city&group_adults=2&no_rooms=1&group_children=0&srpvid=9f5f59e3a2a804ec&srepoch=1754138828&atlas_src=sr_iw_title

If you use the price selector in the left-hand margin of booking.com it allows you to select hotels in your price range (EUR 50 - 100). There are plenty of options in that range although many will be near Brussels-Midi station, so again, you will have to select Grand' Place in the sidebar. Like some of the others here I would look also at hostels. I have stayed at the Sleep Well (Rue du Damier, right next to Rue Neuve). As that was some time ago now I can't really comment on the current state of the hostel, but the location is excellent if you want to be in the middle of the city within walking range of the Grand' Place. It is also very close to a supermarket in the City2 shopping centre.

Good luck, hope you find what you are after.

Lavandula

If you use the price selector in the left-hand margin of booking.com
it allows you to select hotels in your price range (EUR 50 - 100).

Thanks for your recommendation of Sleep Well Hostel. Yes, I'm considering this hostel that you recommend. Thanks so much.

Your advice is quite helpful. At first, I don't realise that booking.com has the price range selector. Wonderful.

I will just add - so that there are no surprises - that Rue du Damier is a dark little side street. However, if you are coming in from Rue Neuve (which is big and bright and has lots of shops), you won't need to linger in that street, the entrance to the hostel is close to Rue de la Blanchisserie which leads into that street from Rue Neuve. Just in the interests of full disclosure :)

Lavandula