Currently, I have an Roth IRA account with Citi bank, but they moved my account to their affiliates. They won't allow me to buy stocks that are below $5 on their site, I have to call them and they will put the transaction for me, but the transaction fee costs more than $100. So Im thinking to swtich to another company, any suggestions ?
In general, Vanguard and Fidelity are both really popular places to open an IRA. The only negative thing about Fidelity is that their Target-date funds are not as good as the equivalent offering from Vanguard. However, if you manage your asset allocation manually, the difference is something of a moot point.
(My Roth IRA is with Fidelity.)
First of all, if Citibank is charging you a transaction fee of $100, you should really dig deeper on that. That doesn't sound correct. Are you sure it is $100?
Since it seems you want to invest very small amounts per month, I would suggest an account with Sharebuilder (http://www.sharebuilder.com). You can set up monthly transactions for a very low fee and you can invest very small amounts. You can buy $5 worth of APPL (http://www.google.com/finance?q=NASDAQ:AAPL) stock. This works by them buying fractional shares for you.
For larger investment amounts, Vanguard (https://personal.vanguard.com/us/whatweoffer/ira/overview) is a good bet as well. Their mutual funds are very low load. Pick a good stock index fund for growth and sit back and relax.
Since Roth IRAs are long term investment accounts, choose a provider that'll be there for you when you retire. There are a number of low cost new entrants, but you don't know long term if they'll be around.
That doesn't mean you should get ripped off with fees! Here are some trusted IRA providers: Vangaurd, Fidelity, Schwab. All of them let you trade commission-free if you trade their ETFs. Fees are nominal for stocks.
If you have $25K or more, WellsTrade is an excellent choice since every trade is commission free.
You can read the reviews and walkthroughs on my site to get a feel of what each site offers.
Since someone took ShareBuilder already, I'll note that Zecco offers roth IRAs, and 10 free trades a month if you have $25,000 in assets ($4.50 otherwise).