>> Like the above topic tilte says, is it the same thing?
No.
>> Or could i go for an arpeggiator without a sequencer if i have a sequencing software already?
Yes
>> .. and whats the cheapest synth i could get for that
Possibly the MicroKorg at City Music for $495. Others may have other suggestion.
BTW sequencing software may come with a arpeggiator function. So check your sequencer 1st.