Salaam!
Det er heilt lovlig å gi bud. Å gi bud for å få kjøpt noe heter "Al Bai'o Man Yaziid" som er lovlig, og Profet Mohammad s.a.w.s. gjorde det selv for en sahabi for at han skulle få tjene mer penger.
Allah vet best!
Se her:
In principle, Islamic law allows sale and purchase of goods / services that are permitted by way of auction in jurisprudence called covenant Bai 'Muzayadah. (Juzzi Ibn Al-Qawanin Al-Fiqhiyah, 290, Majduddin Ibn Taymiyyah, Muntaqal Akhbar, V/101) Practices auction (muzayadah) in a simple form ever done by the Prophet Muhammad, when he was approached by a friend from the Ansar asked for alms to him . Then the Prophet asked: "Is there in your house an asset / goods?" Friends had said that he has a hils (rag) is used as blankets and mats and a qi'b (large wooden cup) used to drink water. Then he told her to take the second item. When he handed it to the Prophet, he took it and offered it: "Who is interested in buying these two things?" Then someone offered them a price of one dirham. So he began to raise its bid: "Who would want to add it again with a dirham?" He said to another bidder: "I bought it for two dirhams" Then the Prophet gave him the item and give two dirhams auction results last Ansari told friends. (Narrated Abu Dawud, al-Nisaa'i and Ibn Majah)